Search results for: hybrid ferro fluid

Authors: Rajiv Kumar Srivastava

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Manufacturing of complex products such as automobiles and computers requires a very large number of parts and sub-assemblies. The design of mechanisms for delivery of these materials to the point of assembly is an important manufacturing system and supply chain challenge. Different approaches to this problem have been evolved for assembly lines designed to make large volumes of standardized products. However, contemporary assembly systems are required to concurrently produce a variety of products using approaches such as mixed model production, and at times even mass customization. In this paper we examine the material supply approaches for variety production in moderate to large volumes. The conventional approach for material delivery to high volume assembly lines is to supply and stock materials line-side. However for certain materials, especially when the same or similar items are used along the line, it is more convenient to supply materials in kits. Kitting becomes more preferable when lines concurrently produce multiple products in mixed model mode, since space requirements could increase as product/ part variety increases. At times such kits may travel along with the product, while in some situations it may be better to have delivery and station-specific kits rather than product-based kits. Further, in some mass customization situations it may even be better to have a single delivery and assembly station, to which an entire kit is delivered for fitment, rather than a normal assembly line. Finally, in low-moderate volume assembly such as in engineered machinery, it may be logistically more economical to gather materials in an order-specific kit prior to launching final assembly. We have studied material supply mechanisms to support assembly systems as observed in case studies of firms with different combinations of volume and variety/ customization. It is found that the appropriate approach tends to be a hybrid between direct line supply and different kitting modes, with the best mix being a function of the manufacturing and supply chain environment, as well as space and handling considerations. In our continuing work we are studying these scenarios further, through the use of descriptive models and progressing towards prescriptive models to help achieve the optimal approach, capturing the trade-offs between inventory, material handling, space, and efficient line supply.

Keywords: assembly systems, kitting, material supply, variety production

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Authors: Murat Emre, Zeynep Tufekcioglu

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Objective: We describe a patient with late onset phenylketonuria which presented with rapidly progressive dementia and parkinsonism that were reversible after management. Background: Phenylketonuria is an autosomal recessive disorder due to mutations in the phenylalanine hydroxlase gene. It normally presents in childhood, in rare cases, however, it may have its onset in adulthood and may mimic other neurological disorders. Case description: A previously normal functioning, 59 year old man was admitted for blurred vision, cognitive impairment and gait difficulty which emerged over the past eight months. In neurological examination he had brisk reflexes, slow gait and left-dominant parkinsonism. Mini-mental state examination score was 25/30, neuropsychological testing revealed a dysexecutive syndrome with constructional apraxia and simultanagnosia. In cranial MRI there were bilateral diffuse hyper-intense lesions in parietal and occipital white matter with no significant atrophy. Electroencephalography showed diffuse slowing with predominance of teta waves. In cerebrospinal fluid examination protein level was slightly elevated (61mg/dL), oligoclonal bands were negative. Electromyography was normal. Routine laboratory examinations for rapidly progressive dementia and parkinsonism were also normal. Serum amino acid levels were determined to explore metabolic leukodystrophies and phenylalanine level was found to be highly elevated (1075 µmol/L) with normal tyrosine (61,20 µmol/L). His cognitive impairment and parkinsonian symptoms improved following three months of phenylalanine restricted diet. Conclusions: Late onset phenylketonuria is a rare, potentially reversible cause of rapidly progressive parkinsonism with dementia. It should be considered in the differential diagnosis of patients with suspicious features.

Keywords: dementia, neurology, Phenylketonuria, rapidly progressive parkinsonism

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Authors: He Li

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Around the mid-1980s, Confucianism was reintroduced into China from Taiwan and Hong Kong as a result of China’s policies of reform and openness. Since then, the revival of neo-Confucianism in mainland China has accelerated and become a crucial component of the public intellectual sphere. The term xinrujia or xinruxue, loosely translated as “neo-Confucianism,” is increasingly understood as an intellectual and cultural phenomenon of the last four decades. The Confucian scholarship is in the process of restoration. This paper examines the Chinese intellectual discourse on Confucianism and democracy and places it in comparative and theoretical perspectives. With China’s rise and surge of populism in the West, particularly in the US, the leading political values of Confucianism could increasingly shape both China and the world at large. This state of affairs points to the need for more systematic efforts to assess the discourse on neo-Confucianism and its implications for China’s transformation. A number of scholars in the camp of neo-Confucianism maintain that some elements of Confucianism are not only compatible with democratic values and institutions but actually promote liberal democracy. They refer to it as Confucian democracy. By contrast, others either view Confucianism as a roadblock to democracy or envision that a convergence of democracy with Confucian values could result in a new hybrid system. The paper traces the complex interplay between Confucianism and democracy. It explores ideological differences between neo-Confucianism and liberal democracy and ascertains whether certain features of neo-Confucianism possess an affinity for the authoritarian political system. In addition to printed materials such as books and journal articles, a selection of articles from the website entitled Confucianism in China will be analyzed. The selection of this website is due to the fact that it is the leading website run by Chinese scholars focusing on neo-Confucianism. Another reason for selecting this website is its accessibility and availability. In the past few years, quite a few websites, left or right, were shut down by the authorities, but this website remains open. This paper explores the core components, dynamics, and implications of neo-Confucianism. My paper is divided into three parts. The first one discusses the origins of neo-Confucianism. The second section reviews the intellectual discourse among Chinese scholars on Confucian democracy. The third one explores the implications of the Chinese intellectual discourse on neo-Confucianism. Recently, liberal democracy has entered more conflict with official ideology. This paper, which is based on my extensive interviews in China prior to the pandemic and analysis of the primary sources in Chinese, will lay the foundation for a chapter on neo-Confucianism and democracy in my next book-length manuscript, tentatively entitled Chinese Intellectual Discourse on Democracy.

Keywords: China, confucius, confucianism, neo-confucianism, democracy

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Authors: Anuj Srivastava, Kuldeep Kumar

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This paper proposes a numerical study of volute tongue design, which affects the centrifugal compressor operating range and pressure recovery. Increased efficiency has been the traditional importance of compressor design. However, the increased operating range has become important in an age of ever-increasing productivity and energy costs in the turbomachinery industry. Efficiency and overall operating range are the two most important parameters studied to evaluate the aerodynamic performance of centrifugal compressor. Volute is one of the components that have significant effect on these two parameters. Choice of volute tongue geometry has major role in compressor performance, also affects performance map. The author evaluates the trade-off on using pull-back tongue geometry on centrifugal compressor performance. In present paper, three different tongue positions and shapes are discussed. These designs are compared in terms of pressure recovery coefficient, pressure loss coefficient, and stable operating range. The detailed flow structures for various volute geometries and pull back angle near tongue are studied extensively to explore the fluid behavior. The viscous Navier-Stokes equations are used to simulate the flow inside the volute. The numerical calculations are compared with thermodynamic 1-D calculations. Author concludes that the increment in compression ratio accompanies with more uniform pressure distribution in the modified tongue shape and location, a uniform static pressure around the circumferential which build a more uniform flow in the impeller and diffuser. Also, the blockage at the tongue of the volute was causing circumferentially nonuniformed pressure along the volute. This nonuniformity may lead impeller and diffuser to operate unstably. However, it is not the volute that directly controls the stall.

Keywords: centrifugal compressor volute, tongue geometry, pull-back, compressor performance, flow instability

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Authors: Hansraj Bookun, Angela Tan, Rachel Xuan, Linheng Zhao, Kejia Wang, Animesh Singla, David Kim, Christopher Loupos

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Introduction: Incisional wound complications in vascular surgery patients represent a significant clinical and econometric burden of morbidity and mortality. The objective of this study was to trial the feasibility of applying the Prevena negative pressure incision management system as a routine dressing in patients who had undergone arterial surgery. Conventionally, Prevena has been applied to groin incisions, but this study features applications on multiple wound sites such as the thigh or major amputation stumps. Method: This was a cross-sectional observational, single-centre case series of 12 patients who had undergone major vascular surgery. Their wounds were managed with the Prevena system being applied either intra-operatively or on the first post-operative day. Demographic and operative details were collated as well as the length of stay and complication rates. Results: There were 9 males (75%) with mean age of 66 years and the comorbid burden was as follows: ischaemic heart disease (92%), diabetes (42%), hypertension (100%), stage 4 or greater kidney impairment (17%) and current or ex-smoking (83%). The main indications were acute ischaemia (33%), claudication (25%), and gangrene (17%). There were single instances of an occluded popliteal artery aneurysm, diabetic foot infection, and rest pain. The majority of patients (50%) had hybrid operations with iliofemoral endarterectomies, patch arterioplasties, and further peripheral endovascular treatment. There were 4 complex arterial bypass operations and 2 major amputations. The mean length of stay was 17 ± 10 days, with a range of 4 to 35 days. A single complication, in the form of a lymphocoele, was encountered in the context of an iliofemoral endarterectomy and patch arterioplasty. This was managed conservatively. There were no deaths. Discussion: The Prevena wound management system shows that in conjunction with safe vascular surgery, absolute wound complication rates remain low and that it remains a valuable adjunct in the treatment of vasculopaths.

Keywords: wound care, negative pressure, vascular surgery, closed incision

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Authors: Ali Javaid, Rizwan Latif, Syed Adnan Qasim, Imran Shafi

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To control combustion inside a direct injection diesel engine, fuel atomization is the best tool. Controlling combustion helps in reducing emissions and improves efficiency. Cavitation is one of the most important factors that significantly affect the nature of spray before it injects into combustion chamber. Typical fuel injector nozzles are small and operate at a very high pressure, which limits the study of internal nozzle behavior especially in case of diesel engine. Simulating cavitation in a fuel injector will help in understanding the phenomenon and will assist in further development. There is a parametric variation between high speed and high torque low speed diesel engines. The objective of this study is to simulate internal spray characteristics for a low speed high torque diesel engine. In-nozzle cavitation has strong effects on the parameters e.g. mass flow rate, fuel velocity, and momentum flux of fuel that is to be injected into the combustion chamber. The external spray dynamics and subsequently the air – fuel mixing depends on a lot of the parameters of fuel injecting the nozzle. The approach used to model turbulence induced in – nozzle cavitation for high-torque low-speed diesel engine, is homogeneous equilibrium model. The governing equations were modeled using Matlab. Complete Model in question was extensively evaluated by performing 3-D time-dependent simulations on Open FOAM, which is an open source flow solver and implemented in CFD (Computational Fluid Dynamics). Results thus obtained will be analyzed for better evaporation in the near-nozzle region. The proposed analyses will further help in better engine efficiency, low emission, and improved fuel economy.

Keywords: cavitation, HEM model, nozzle flow, open foam, turbulence

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Authors: Ruth Diego, Luis M. Romeo, Antonio Morán

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In the present work, a study of the coupling of a Bioelectrochemical System together with an oxy-combustion boiler is carried out; specifically, it proposes to connect the combustion gas outlet of a boiler with a microbial electrolysis cell (MEC) where the CO2 from the gases are transformed into methane in the cathode chamber, and the oxygen produced in the anode chamber is recirculated to the oxy-combustion boiler. The MEC mainly consists of two electrodes (anode and cathode) immersed in an aqueous electrolyte; these electrodes are separated by a proton exchange membrane (PEM). In this case, the anode is abiotic (where oxygen is produced), and it is at the cathode that an electroactive biofilm is formed with microorganisms that catalyze the CO2 reduction reactions. Real data from an oxy-combustion process in a boiler of around 20 thermal MW have been used for this study and are combined with data obtained on a smaller scale (laboratory-pilot scale) to determine the yields that could be obtained considering the system as environmentally sustainable energy storage. In this way, an attempt is made to integrate a relatively conventional energy production system (oxy-combustion) with a biological system (microbial electrolysis cell), which is a challenge to be addressed in this type of new hybrid scheme. In this way, a novel concept is presented with the basic dimensioning of the necessary equipment and the efficiency of the global process. In this work, it has been calculated that the efficiency of this power-to-gas system based on MEC cells when coupled to industrial processes is of the same order of magnitude as the most promising equivalent routes. The proposed process has two main limitations, the overpotentials in the electrodes that penalize the overall efficiency and the need for storage tanks for the process gases. The results of the calculations carried out in this work show that certain real potentials achieve an acceptable performance. Regarding the tanks, with adequate dimensioning, it is possible to achieve complete autonomy. The proposed system called OxyMES provides energy storage without energetically penalizing the process when compared to an oxy-combustion plant with conventional CO2 capture. According to the results obtained, this system can be applied as a measure to decarbonize an industry, changing the original fuel of the oxy-combustion boiler to the biogas generated in the MEC cell. It could also be used to neutralize CO2 emissions from industry by converting it to methane and then injecting it into the natural gas grid.

Keywords: microbial electrolysis cells, oxy-combustion, co2, power-to-gas

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Authors: José Alberto García Fernández, Zhimin Du, Xinqiao Jin

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Nowadays, data center industry faces strong challenges for increasing the speed and data processing capacities while at the same time is trying to keep their devices a suitable working temperature without penalizing that capacity. Consequently, the cooling systems of this kind of facilities use a large amount of energy to dissipate the heat generated inside the servers, and developing new cooling techniques or perfecting those already existing would be a great advance in this type of industry. The installation of a temperature sensor matrix distributed in the structure of each server would provide the necessary information for collecting the required data for obtaining a temperature profile instantly inside them. However, the number of temperature probes required to obtain the temperature profiles with sufficient accuracy is very high and expensive. Therefore, other less intrusive techniques are employed where each point that characterizes the server temperature profile is obtained by solving differential equations through simulation methods, simplifying data collection techniques but increasing the time to obtain results. In order to reduce these calculation times, complicated and slow computational fluid dynamics simulations are replaced by simpler and faster finite element method simulations which solve the Burgers‘ equations by backward, forward and central discretization techniques after simplifying the energy and enthalpy conservation differential equations. The discretization methods employed for solving the first and second order derivatives of the obtained Burgers‘ equation after these simplifications are the key for obtaining results with greater or lesser accuracy regardless of the characteristic truncation error.

Keywords: Burgers' equations, CFD simulation, data center, discretization methods, FEM simulation, temperature profile

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Authors: Shamsul Chowdhury

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The objective of this paper is to present the detailed analysis of the turbulent wave boundary layer produced by progressive finite-amplitude waves theory. Most of the works have done for the mass transport in the turbulent boundary layer assuming the eddy viscosity is not time varying, where the sediment movement is induced by the mean velocity. Near the ocean bottom, the waves produce a thin turbulent boundary layer, where the flow is highly rotational, and shear stress associated with the fluid motion cannot be neglected. The magnitude and the predominant direction of the sediment transport near the bottom are known to be closely related to the flow in the wave induced boundary layer. The magnitude of water particle velocity at the Crest phase differs from the one of the Trough phases due to the non-linearity of the waves, which plays an important role to determine the sediment movement. The non-linearity of the waves become predominant in the surf zone area, where the sediment movement occurs vigorously. Therefore, in order to describe the flow near the bottom and relationship between the flow and the movement of the sediment, the analysis was done using the non-linear boundary layer equation and the finite amplitude wave theory was applied to represent the velocity fields in the turbulent wave boundary layer. At first, the calculation was done for turbulent wave boundary layer by two-dimensional model where throughout the calculation is non-linear. But Stokes second order wave profile is adopted at the upper boundary. The calculated profile was compared with the experimental data. Finally, the calculation is done based on various modes of the velocity and turbulent energy. The mean velocity is found to differ from condition of the relative depth and the roughness. It is also found that due to non-linearity, the absolute value for velocity and turbulent energy as well as Reynolds stress are asymmetric. The mean velocity of the laminar boundary layer is always positive but in the turbulent boundary layer plays a very complicated role.

Keywords: wave boundary, mass transport, mean velocity, shear stress

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Authors: Xiaoyu Shen, Fang Fang, Chujun Qiu

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Herewith we present a Fourier method for credit risk quantification and allocation in the factor-copula model framework. The key insight is that, compared to directly computing the cumulative distribution function of the portfolio loss via Monte Carlo simulation, it is, in fact, more efficient to calculate the transformation of the distribution function in the Fourier domain instead and inverting back to the real domain can be done in just one step and semi-analytically, thanks to the popular COS method (with some adjustments). We also show that the Euler risk allocation problem can be solved in the same way since it can be transformed into the problem of evaluating a conditional cumulative distribution function. Once the conditional or unconditional cumulative distribution function is known, one can easily calculate various risk metrics. The proposed method not only fills the niche in literature, to the best of our knowledge, of accurate numerical methods for risk allocation but may also serve as a much faster alternative to the Monte Carlo simulation method for risk quantification in general. It can cope with various factor-copula model choices, which we demonstrate via examples of a two-factor Gaussian copula and a two-factor Gaussian-t hybrid copula. The fast error convergence is proved mathematically and then verified by numerical experiments, in which Value-at-Risk, Expected Shortfall, and conditional Expected Shortfall are taken as examples of commonly used risk metrics. The calculation speed and accuracy are tested to be significantly superior to the MC simulation for real-sized portfolios. The computational complexity is, by design, primarily driven by the number of factors instead of the number of obligors, as in the case of Monte Carlo simulation. The limitation of this method lies in the "curse of dimension" that is intrinsic to multi-dimensional numerical integration, which, however, can be relaxed with the help of dimension reduction techniques and/or parallel computing, as we will demonstrate in a separate paper. The potential application of this method has a wide range: from credit derivatives pricing to economic capital calculation of the banking book, default risk charge and incremental risk charge computation of the trading book, and even to other risk types than credit risk.

Keywords: credit portfolio, risk allocation, factor copula model, the COS method, Fourier method

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Authors: Pedro Esteban

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Most installations nowadays are exposed to many power quality problems, and they also face numerous challenges to comply with grid code and energy efficiency requirements. The reason behind this is that they are not designed to support nonlinear, non-balanced, and variable loads and generators that make up a large percentage of modern electric power systems. These problems and challenges become especially critical when designing green buildings and smart cities. These problems and challenges are caused by equipment that can be typically found in these installations like variable speed drives (VSD), transformers, lighting, battery chargers, double-conversion UPS (uninterruptible power supply) systems, highly dynamic loads, single-phase loads, fossil fuel generators and renewable generation sources, to name a few. Moreover, events like capacitor switching (from existing capacitor banks or passive harmonic filters), auto-reclose operations of transmission and distribution lines, or the starting of large motors also contribute to these problems and challenges. Active power filters (APF) are one of the fastest-growing power electronics technologies for solving power quality problems and meeting grid code and energy efficiency requirements for a wide range of segments and applications. They are a high performance, flexible, compact, modular, and cost-effective type of power electronics solutions that provide an instantaneous and effective response in low or high voltage electric power systems. They enable longer equipment lifetime, higher process reliability, improved power system capacity and stability, and reduced energy losses, complying with most demanding power quality and energy efficiency standards and grid codes. There can be found several types of active power filters, including active harmonic filters (AHF), static var generators (SVG), active load balancers (ALB), hybrid var compensators (HVC), and low harmonic drives (LHD) nowadays. All these devices can be used in applications in Smart Cities bringing several technical and economic benefits.

Keywords: power quality improvement, energy efficiency, grid code compliance, green buildings, smart cities

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Authors: Gökçen A. Çiftçioğlu, M. A. Neşet Kadırgan, Figen Kadırgan

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Solar energy, since it is available every day, is seen as one of the most valuable renewable energy resources. Thus, the energy of sun should be efficiently used in various applications. The most known applications that use solar energy are heating water and spaces. High efficiency solar collectors need appropriate selective surfaces to absorb the heat. Selective surfaces (Selektif-Sera) used in this study are applied to flat collectors, which are produced by a roll to roll cost effective coating of nano nickel layers, developed in Selektif Teknoloji Co. Inc. Efficiency of flat collectors using Selektif-Sera absorbers are calculated in collaboration with Institute for Solar Technik Rapperswil, Switzerland. The main cause of high energy consumption in industry is mostly caused from low temperature level processes. There is considerable effort in research to minimize the energy use by renewable energy sources such as solar energy. A feasibility study will be presented to obtain the potential of solar thermal energy utilization in the textile industry using these solar collectors. For the feasibility calculations presented in this study, textile dyeing and finishing factory located at Kahramanmaras is selected since the geographic location was an important factor. Kahramanmaras is located in the south east part of Turkey thus has a great potential to have solar illumination much longer. It was observed that, the collector area is limited by the available area in the factory, thus a hybrid heating generating system (lignite/solar thermal) was preferred in the calculations of this study to be more realistic. During the feasibility work, the calculations took into account the preheating process, where well waters heated from 15 °C to 30-40 °C by using the hot waters in heat exchangers. Then the preheated water was heated again by high efficiency solar collectors. Economic comparison between the lignite use and solar thermal collector use was provided to determine the optimal system that can be used efficiently. The optimum design of solar thermal systems was studied depending on the optimum collector area. It was found that the solar thermal system is more economic and efficient than the merely lignite use. Return on investment time is calculated as 5.15 years.

Keywords: energy, renewable energy, selective surface, solar collector

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Authors: Katharina Kargel, Frederic Vobbe

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Sexualized violence against children and adolescents using digital media poses particular challenges for practitioners with a focus on crisis intervention (social work, psychotherapy, law enforcement). The technical delimitation of violence increases the burden on those affected and increases the complexity of interdisciplinary cooperation. Urgently needed recommendations for practical action do not yet exist in Germany. Funded by the Federal Ministry of Education and Research, these recommendations for action are being developed in the HUMAN project together with science and practice. The presentation introduces the participatory approach of the HUMAN project. We discuss the application-oriented, casuistic approach of the project and present its results using the example of concrete case-based recommendations for Action. The participants will be presented with concrete prototypical case studies from the project, which will be used to illustrate quality criteria for crisis intervention in cases of sexualized violence using digital media. On the basis of case analyses, focus group interviews and interviews with victims of violence, we present the six central challenges of sexualized violence with the use of digital media, namely: • Diffusion (Ambiguities regarding the extent and significance of violence) , • Transcendence (Space and time independence of the dynamics of violence, omnipresence), • omnipresent anxiety (considering diffusion and transcendence), • being haunted (repeated confrontation with digital memories of violence or the perpetrator), • disparity (conflicts of interpretative power between those affected and the social environment) • simultaneity (of all other factors). We point out generalizable principles with which these challenges can be dealt with professionally. Dealing professionally with sexualized violence using digital media requires a stronger networking of professional actors. A clear distinction must be made between their own mission and the mission of the network partners. Those affected by violence must be shown options for crisis intervention in the context of the aid networks. The different competencies and the professional mission of the offers of help are to be made transparent. The necessity of technical possibilities for deleting abuse images beyond criminal prosecution will be discussed. Those affected are stabilized by multimodal strategies such as a combination of rational emotive therapy, legal support and technical assistance.

Keywords: sexualized violence, intervention, digital media, children and youth

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Authors: Ndarusanze Berchmans

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This research work focused on the analysis of the observations of tuberculous meningitis in HIV-positive patients who were treated by the Prince Regent Charles Hospital in Bujumbura. A number of 246 seropositive patients were examined by the laboratory of Prince Regent Charles in the period between 2010 and 2015. We did a retrospective study; we used data from the registers of the laboratories mentioned above; the objective was to approach the epidemiological, biological, clinical, and therapeutic characteristics of tuberculosis meningitis infection: 124 women (50.40% of AIDS patients) and 122 men (49.59% of AIDS patients) were subject to the diagnosis by identification of cerebrospinal fluid (CSF). The average age of the patients was 30 years for this period. The population at risk has an average age of between 34 and 42 years for the years between 2010-2015. From 2010 to 2012, cases of opportunistic diseases (e.g., tuberculous meningitis and Cryptococcus neoformans meningitis), often found in immunocompromised, were observed at a high rate; in this period, there was a disturbance of the rhythm providing antiretroviral drugs to people with AIDS. The rate of the two meningitis (tuberculous meningitis and Cryptococcus neoformans meningitis) remained above 10% to gradually decrease until 2015, with the gradual return of antiretrovirals. This period records an overall average of 25 cases of tuberculous meningitis, or a percentage of 10.16%. For the year 2015, there were 4 cases of tuberculous meningitis out of a total of 35 seropositive examined (11.42%). This year's percentage shows that the number of tuberculous meningitis cases has fallen from the rate in previous years. This is the result of the care given by associations against HIV/AIDS to HIV-positive people. This decrease in cases of tuberculous meningitis is due to the acquisition of antiretrovirals by all HIV-positive people treated by hospitals. For the moment, these hospitals are taking care of many AIDS patients by providing them permanently with antiretrovirals; Besides that, there are many patients who are supported by associations whose activities are directed against HIV/AIDS.

Keywords: Cryptococcus neoformans meningitis, tuberculosis meningitis, neurological complications, epidemiology of meningitis

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Authors: Ajith Kumar S., Sankaran Namboothiri, Sankrish J., SarathKumar S., S. Anil Lal

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A numerical analysis of flow over a heated circular cylinder is done in this paper. The governing equations, Navier-Stokes, and energy equation within the Boussinesq approximation along with continuity equation are solved using hybrid FEM-FVM technique. The density gradient created due to the heating of the cylinder will induce buoyancy force, opposite to the direction of action of acceleration due to gravity, g. In the present work, the flow direction and the direction of buoyancy force are taken as same (vertical flow configuration), so that the buoyancy force accelerates the mean flow past the cylinder. The relative dominance of the buoyancy force over the inertia force is characterized by the Richardson number (Ri), which is one of the parameter that governs the flow dynamics and heat transfer in this analysis. It is well known that above a certain value of Reynolds number, Re (ratio of inertia force over the viscous forces), the unsteady Von Karman vortices can be seen shedding behind the cylinder. The shedding wake patterns could be seriously altered by heating/cooling the cylinder. The non-dimensional shedding frequency called the Strouhal number is found to be increasing as Ri increases. The aerodynamic force coefficients CL and CD are observed to change its value. In the present vertical configuration of flow over the cylinder, as Ri increases, shedding frequency gets increased and suddenly drops down to zero at a critical value of Richardson number. The unsteady vortices turn to steady standing recirculation bubbles behind the cylinder after this critical Richardson number. This phenomenon is well known in literature as "Breakdown of the Karman Vortex Street". It is interesting to see the flow structures on further increase in the Richardson number. On further heating of the cylinder surface, the size of the recirculation bubble decreases without loosing its symmetry about the horizontal axis passing through the center of the cylinder. The separation angle is found to be decreasing with Ri. Finally, we observed a second critical Richardson number, after which the the flow will be attached to the cylinder surface without any wake behind it. The flow structures will be symmetrical not only about the horizontal axis, but also with the vertical axis passing through the center of the cylinder. At this stage, there will be a "single plume" emanating from the rear stagnation point of the cylinder. We also observed the transition of the plume is a strong function of the Richardson number.

Keywords: drag reduction, flow over circular cylinder, flow control, mixed convection flow, vortex shedding, vortex breakdown

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Authors: David W. Taylor, Fernando Lourenço, Carolyn Branston, Paul Tucker

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There are an increasing number of students at Universities in the United Kingdom engaging in entrepreneurship role-play to explore business start-up as a career alternative to employment. These role-play activities have been shown to have a positive influence on students’ entrepreneurial intentions. Universities also play a role in developing graduates’ awareness of social responsibility. However, social responsibility is often missing from these entrepreneurship role-plays. It is important that these role-play activities include the development of values that support social responsibility, in-line with those running hybrid, humane and sustainable enterprises, and not simply focus on profit. The Young Enterprise (YE) Start-Up programme is an example of a role-play activity that is gaining in popularity amongst United Kingdom Universities seeking ways to give students insight into a business start-up. A Post-92 University in the North-West of England has adapted the traditional YE Directorship roles (e.g., Marketing Director, Sales Director) by including a Corporate Social Responsibility (CSR) Director in all of the team-based YE Start-Up businesses. The aim for introducing this Directorship was to observe if such a role would help create a more socially responsible value-system within each company and in turn shape business decisions. This paper investigates role-play as a tool to help enterprise educators develop socially responsible attitudes and values in nascent entrepreneurs. A mixed qualitative methodology approach has been used, which includes interviews, role-play, and reflection, to help students develop positive value characteristics through the exploration of unethical and selfish behaviors. The initial findings indicate that role-play helped CSR Directors learn and gain insights into the importance of corporate social responsibility, influenced the values and actions of their YE Start-Ups, and increased the likelihood that if the participants were to launch a business post-graduation, that the intent would be for the business to be socially responsible. These findings help inform educators on how to develop socially responsible nascent entrepreneurs within a traditionally profit orientated business model.

Keywords: student entrepreneurship, young enterprise, social responsibility, role-play, values

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Authors: Arshad Ali

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The Taliban insurgency in Swat which started apparently as a social movement in 2004 transformed into an anti-Pakistan Islamist insurgency by joining hands with the Tehrik-e-Taliban Pakistan (TTP) upon its formation in 2007. It quickly spread beyond Swat by 2009 making Swat the second stronghold of TTP after FATA. It prompted the Pakistan military to launch a full-scale counterinsurgency military operation code named Rah-i-Rast to regain the control of Swat. Operation Rah-i-Rast was successful not only in restoring the writ of the State but more importantly in creating a consensus against the spread of Taliban insurgency in Pakistan at political, social and military levels. This operation became a test case for civilian government and military to seek for a sustainable solution combating the TTP insurgency in the north-west of Pakistan. This study analyzes why the counterinsurgency operation Rah-i-Rast was successful and why the previous ones came into failure. The study also explores factors which created consensus against the Taliban insurgency at political and social level as well as reasons which hindered such a consensual approach in the past. The study argues that the previous initiatives failed due to various factors including Pakistan army’s lack of comprehensive counterinsurgency model, weak political will and public support, and states negligence. Also, the initial counterinsurgency policies were ad-hoc in nature fluctuating between military operations and peace deals. After continuous failure, the military revisited its approach to counterinsurgency in the operation Rah-i-Rast. The security forces learnt from their past experiences and developed a pragmatic counterinsurgency model: ‘clear, hold, build, and transfer.’ The military also adopted the population-centric approach to provide security to the local people. This case Study of Swat evaluates the strengths and weaknesses of the Pakistan's counterinsurgency operations as well as peace agreements. It will analyze operation Rah-i-Rast in the light of David Galula’s model of counterinsurgency. Unlike existing literature, the study underscores the bottom up approach adopted by the Pakistan’s military and government by engaging the local population to sustain the post-operation stability in Swat. More specifically, the study emphasizes on the hybrid counterinsurgency model “clear, hold, and build and Transfer” in Swat.

Keywords: Insurgency, Counterinsurgency, clear, hold, build, transfer

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Authors: Sherman Ho, Ahmed Cherif Megri

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Headers play a critical role in conveying steam to regulate heating system temperatures. While various materials like steel grades 91 and 92 have been traditionally used for pipes, this research proposes the use of a robust and innovative material, INCONEL Alloy 740H. Boilers in power plant configurations are exposed to cycling conditions due to factors such as daily, seasonal, and yearly variations in weather. These cycling conditions can lead to the deterioration of headers, which are vital components with intricate geometries. Header failures result in substantial financial losses from repair costs and power plant shutdowns, along with significant public inconveniences such as the loss of heating and hot water. To address this issue and seek solutions, a mechanical analysis, as well as a structural analysis, are recommended. Transient analysis to predict heat transfer conditions is of paramount importance, as the direction of heat transfer within the header walls and the passing steam can vary based on the location of interest, load, and operating conditions. The geometry and material of the header are also crucial design factors, and the choice of pipe material depends on its usage. In this context, the heat transfer coefficient plays a vital role in header design and analysis. This research employs ANSYS Fluent, a numerical simulation program, to understand header behavior, predict heat transfer, and analyze mechanical phenomena within the header. Transient simulations are conducted to investigate parameters like heat transfer coefficient, pressure loss coefficients, and heat flux, with the results used to optimize header design.

Keywords: CFD, header, power plant, heat transfer coefficient, simulation using experimental data

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Authors: Spase Janevski

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We, as designers, should be aware of the consequences of our material selection, at the early stages of the design process. Some of the designer’s decisions can have a very significant impact on design for sustainability. The influence of this concept has led to years of research studies into eco-friendly materials and their potentials for creating new sustainable products. In order to answer the question, 'how cork has become a design trend', this paper will present an overview of the implications of the concept of design for sustainability on the potential uses of cork material. A decade ago, cork as a material had an association with wine stoppers, but with the evolution of sustainable product design as part of the concept of design for sustainability, cork now offers product designers a wide range of new materials and applications. The purpose of this paper is to show how the phenomenon of sustainability has had an impact on the progress of the material which is currently not being an integral component of the design material palette. At the beginning, the nature of the relationship between cork and sustainability will be explained through the following stages: 1) fundamental understanding of the concept of Design for Sustainability and the importance of material selection for sustainable product design, and 2) the importance of cork oak trees for the environment and the environmental impacts of cork products. In order to examine and present the influence of the sustainability on the innovation in cork applications, the paper will provide a historical overview of designing with cork. The overview will consist of four stages: 1) pre-industrial period - the period when ancient nations used cork and amphoras to store their wine; 2) industrial period - emergence and industrialization of well-known wine stoppers; 3) post-industrial period - commercializing cork products in the area of floors and coverings and first developments in industrial research; and 4) the period when large cork realized the importance of sustainability and started to focus more markedly on research and development. The existence of new cork materials, the investigation in new applications and the investment in new innovations have proved that the sustainability approach has had a great influence on the revival of this material. In addition, the paper will present some of the new cork innovative materials and applications and their potentials for designing promising and sustainable solutions with additive manufacturing technologies, such as 3D printing. Lastly, the paper will introduce some questions for further study, such as the environmental impacts of the new hybrid materials and the gap between cork industry and cork research and development teams. The paper concludes by stating that cork is not only a material for wine stoppers anymore, thanks to the awareness of the concept of design for sustainability.

Keywords: cork, design for sustainability, innovation, sustainable materials

Procedia PDF Downloads 81

Authors: Mudassir Ghafoor, Irsalan Arif, Shuaib Salamat

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This paper presents modeling and analysis of different intake bump (compression surface) configurations and comparison with an existing supersonic aircraft having bump intake configuration. Many successful aircraft models have shown that Diverter less Supersonic Inlet (DSI) as compared to conventional intake can reduce weight, complexity and also maintenance cost. The research is divided into two parts. In the first part, four different intake bumps are modeled for comparative analysis keeping in view the consistency of outer perimeter dimensions of fighter aircraft and various characteristics such as flow behavior, boundary layer diversion and pressure recovery are analyzed. In the second part, modeled bumps are integrated with intake duct for performance analysis and comparison with existing supersonic aircraft data is carried out. The bumps are named as uniform large (Config 1), uniform small (Config 2), uniform sharp (Config 3), non-uniform (Config 4) based on their geometric features. Analysis is carried out at different Mach Numbers to analyze flow behavior in subsonic and supersonic regime. Flow behavior, boundary layer diversion and Pressure recovery are examined for each bump characteristics, and comparative study is carried out. The analysis reveals that at subsonic speed, Config 1 and Config 2 give similar pressure recoveries as diverterless supersonic intake, but difference in pressure recoveries becomes significant at supersonic speed. It was concluded from research that Config 1 gives better results as compared to Config 3. Also, higher amplitude (Config 1) is preferred over lower (Config 2 and 4). It was observed that maximum height of bump is preferred to be placed near cowl lip of intake duct.

Keywords: bump intake, boundary layer, computational fluid dynamics, diverter-less supersonic inlet

Procedia PDF Downloads 222

Authors: Brennan Lodge

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Amidst a complex regulatory landscape, Retrieval Augmented Generation (RAG) emerges as a transformative tool for Governance Risk and Compliance (GRC) officers. This paper details the application of RAG in synthesizing Large Language Models (LLMs) with external knowledge bases, offering GRC professionals an advanced means to adapt to rapid changes in compliance requirements. While the development for standalone LLM’s (Large Language Models) is exciting, such models do have their downsides. LLM’s cannot easily expand or revise their memory, and they can’t straightforwardly provide insight into their predictions, and may produce “hallucinations.” Leveraging a pre-trained seq2seq transformer and a dense vector index of domain-specific data, this approach integrates real-time data retrieval into the generative process, enabling gap analysis and the dynamic generation of compliance and risk management content. We delve into the mechanics of RAG, focusing on its dual structure that pairs parametric knowledge contained within the transformer model with non-parametric data extracted from an updatable corpus. This hybrid model enhances decision-making through context-rich insights, drawing from the most current and relevant information, thereby enabling GRC officers to maintain a proactive compliance stance. Our methodology aligns with the latest advances in neural network fine-tuning, providing a granular, token-level application of retrieved information to inform and generate compliance narratives. By employing RAG, we exhibit a scalable solution that can adapt to novel regulatory challenges and cybersecurity threats, offering GRC officers a robust, predictive tool that augments their expertise. The granular application of RAG’s dual structure not only improves compliance and risk management protocols but also informs the development of compliance narratives with pinpoint accuracy. It underscores AI’s emerging role in strategic risk mitigation and proactive policy formation, positioning GRC officers to anticipate and navigate the complexities of regulatory evolution confidently.

Keywords: cybersecurity, gen AI, retrieval augmented generation, cybersecurity defense strategies

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Authors: Ewa Kicko Walczak, Grazyna Rymarz

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In recent years, nanotechnology has been successfully applied for flame retardancy of polymers, in particular for construction materials. The consumption of thermoset resins as a construction polymers materials is approximately over one million tone word wide. Excellent mechanical, relatively high heat and thermal stability of their type of polymers are proven for variety applications, e.g. transportation, electrical, electronic, building part industry. Above applications in addition to the strength and thermal properties also requires -referring to the legal regulation or recommendation - an adequate level of flammability of the materials. This publication present the evaluation was made of effectiveness of flame retardancy of halogen-free hybrid flame retardants(FR) as compounds nitric/phosphorus modifiers that act with nanofillers (nano carbons, organ modified montmorillonite, nano silica, microsphere) in relation to unsaturated polyester/epoxy resins and glass-reinforced on base this resins laminates(GRP) as a final products. The analysis of the fire properties provided proof of effective flame retardancy of the tested composites by defining oxygen indices values (LOI), with the use of thermogravimetric methods (TGA) and combustion head (CH). An analysis of the combustion process with Cone Calorimeter (CC) method included in the first place N/P units and nanofillers with the observed phenomenon of synergic action of compounds. The fine-plates, phase morphology and rheology of composites were assessed by SEM/ TEM analysis. Polymer-matrix glass reinforced laminates with modified resins meet LOI over 30%, reduced in a decrease by 70% HRR (according to CC analysis), positive description of the curves TGA and values CH; no adverse negative impact on mechanical properties. The main objective of our current project is to contribute to the general understanding of the flame retardants mechanism and to investigate the corresponding structure/properties relationships. We confirm that nanotechnology systems are successfully concept for commercialized forms for non-flammable GRP pipe, concrete composites, and flame retardant tunnels constructions.

Keywords: fire retardants, FR, halogen-free FR nanofillers, non-flammable pipe/concrete, thermoset resins

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Authors: Devesh Motwani, Ranjana S. Baruah

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The prime incentive behind up gradation of heavy oil is to increase its API gravity for ease of transportation to refineries, thus expanding the market access of bitumen-based crude to the refineries. There has always been a demand for an integrated approach that aims at simplifying the upgrading scheme, making it adaptable to the production site in terms of economics, environment, and personnel safety. Recent advances in nanotechnology have facilitated the development of two lines of heavy oil upgrading processes that make use of nano-catalysts for producing upgraded oil: In Situ Upgrading and Field Upgrading. The In-Situ upgrading scheme makes use of Hot Fluid Injection (HFI) technique where heavy fractions separated from produced oil are injected into the formations to reintroduce heat into the reservoir along with suspended nano-catalysts and hydrogen. In the presence of hydrogen, catalytic exothermic hydro-processing reactions occur that produce light gases and volatile hydrocarbons which contribute to increased oil detachment from the rock resulting in enhanced recovery. In this way the process is a combination of enhanced heavy oil recovery along with up gradation that effectively handles the heat load within the reservoirs, reduces hydrocarbon waste generation and minimizes the need for diluents. By eliminating most of the residual oil, the Synthetic Crude Oil (SCO) is much easier to transport and more amenable for processing in refineries. For heavy oil reservoirs seriously impacted by the presence of aquifers, the nano-catalytic technology can still be implemented on field though with some additional investments and reduced synergies; however still significantly serving the purpose of production of transportable oil with substantial benefits with respect to both large scale upgrading, and known commercial field upgrading technologies currently on the market. The paper aims to delve deeper into the technology discussed, and the future compatibility.

Keywords: upgrading, synthetic crude oil, nano-catalytic technology, compatibility

Procedia PDF Downloads 383

Authors: Arman Kishan, Mark Haft, Steve Li, Duc Nguyen, Dawn Laporte

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Objective: Patients with Type 2 diabetes (T2DM) often face higher postoperative complication rates. Limited data exist on outcomes in T2DM patients undergoing carpal tunnel release (CTR). This study aims to compare complication rates between endoscopic CTR (ECTR) and open CTR (OCTR) in patients with T2DM. Methods: This was a retrospective cohort study using the TriNetX database of 56741 patients with T2DM undergoing ECTR (N= 14,949) or OCTR (N= 41,792). Demographic data, medical comorbidities, and complication rates were analyzed. We used multivariable analysis to identify differences in postoperative complication rates between the two treatment methods in patients with T2DM. Results: Patients with T2DM undergoing ECTR had a significantly lower incidence of 90-day wound infection (p < 0.001), 90-day wound dehiscence (p < 0.001), and nerve injury (p < 0.001) when compared to patients who underwent OCTR. After matching, there was a significantly higher number of T2DM patients undergoing ECTR who had peripheral vascular disease (p = 0.045) and hypertension (p = 0.020) when compared to the OCTR group. These patients also had a lower incidence of fluid and electrolyte disorders (p = 0.002) and chronic blood loss anemia (p = 0.025). Conclusion: ECTR presents a superior choice for T2DM patients undergoing CTR, yielding significantly lower rates of wound infection, wound dehiscence, and nerve injury within 90 days post-surgery—reducing the risk by 31%, 48%, and 59%, respectively. These findings support the adoption of ECTR as the preferred method in this patient population, potentially leading to improved postoperative outcomes.

Keywords: endoscopic treatment of carpal tunnel syndrome, open treatment of carpal tunnel syndrome, carpal tunnel syndrome, postoperative complications in patients with diabetes mellitus

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Authors: Desplanches Maxime

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Accurate estimation of the remaining useful life of lithium-ion batteries for electronic devices is crucial. Data-driven methodologies encounter challenges related to data volume and acquisition protocols, particularly in capturing a comprehensive range of aging indicators. To address these limitations, we propose a hybrid approach that integrates an electrochemical model with state-of-the-art data analysis techniques, yielding a comprehensive database. Our methodology involves infusing an aging phenomenon into a Newman model, leading to the creation of an extensive database capturing various aging states based on non-destructive parameters. This database serves as a robust foundation for subsequent analysis. Leveraging advanced data analysis techniques, notably principal component analysis and t-Distributed Stochastic Neighbor Embedding, we extract pivotal information from the data. This information is harnessed to construct a regression function using either random forest or support vector machine algorithms. The resulting predictor demonstrates a 5% error margin in estimating remaining battery life, providing actionable insights for optimizing usage. Furthermore, the database was built from the Newman model calibrated for aging and performance using data from a European project called Teesmat. The model was then initialized numerous times with different aging values, for instance, with varying thicknesses of SEI (Solid Electrolyte Interphase). This comprehensive approach ensures a thorough exploration of battery aging dynamics, enhancing the accuracy and reliability of our predictive model. Of particular importance is our reliance on the database generated through the integration of the electrochemical model. This database serves as a crucial asset in advancing our understanding of aging states. Beyond its capability for precise remaining life predictions, this database-driven approach offers valuable insights for optimizing battery usage and adapting the predictor to various scenarios. This underscores the practical significance of our method in facilitating better decision-making regarding lithium-ion battery management.

Keywords: Li-ion battery, aging, diagnostics, data analysis, prediction, machine learning, electrochemical model, regression

Procedia PDF Downloads 39

Authors: Eda Jazexhiu-Postoli, Gladiola Hoxha, Ada Simeoni, Sonila Biba

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Background Neonatal hypotonia represents a commonly encountered issue in the Neonatal Intensive Care Unit and newborn nursery. The differential diagnosis is broad, encompassing chromosome abnormalities, primary muscular dystrophies, neuropathies and inborn errors of metabolism. Aim of study Our study describes some of the main clinical features of hypotonia in newborns and presents clinical cases of neonatal hypotonia we treated in our Neonatal unit in the last 3 years. Case reports Four neonates born in our hospital presented with hypotonia after birth, one preterm newborn 35-36 weeks of gestational age and three other term newborns (38-39 weeks of gestational age). Prenatal data revealed a decrease in fetal movements in both cases. Intrapartum meconium-stained amniotic fluid was found in 75% of our hypotonic newborns. Clinical features included inability to establish effective respiratory movements and need for resuscitation in the delivery room, respiratory distress syndrome, feeding difficulties and need for oro-gastric tube feeding, dysmorphic features, hoarse voice and moderate to severe muscular hypotonia. The genetic workup revealed the diagnosis of Autosomal Recessive Congenital Myasthenic Syndrome 1-B, Sotos Syndrome, Spinal Muscular Atrophy Type 1 and Transient Hypotonia of the Newborn. Two out of four hypotonic neonates were transferred to the Pediatric Intensive Care Unit and died at the age of three to five months old. Conclusion Hypotonia is a concerning finding in neonatal care and it is suggested by decreased intrauterine fetal movements, failure to establish first breaths, respiratory distress and feeding difficulties in the neonate. Prognosis is determined by its etiology and time of diagnosis and intervention.

Keywords: hypotonic neonate, respiratory distress, feeding difficulties, fetal movements

Procedia PDF Downloads 79

Authors: Panagiota A. Kotsoni, George S. Ypsilandis

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Learning an L2 is a demanding process for all students and in particular for those with learning disabilities (LD) who demonstrate an inability to catch up with their classmates’ progress in a given period of time. This area of study, i.e. examining children with learning disabilities in L2 has not (yet) attracted the growing interest that is registered in L1 and thus remains comparatively neglected. It is this scientific field that this study wishes to contribute to. The longitudinal purpose of this study is to locate effective Supportive Feedback Strategies (SFS) and add to the quality of learning in second language vocabulary in both typically developing (TD) and LD children. Specifically, this study aims at investigating and comparing the performance of TD with LD children on two different types of SFSs related to vocabulary short and long-term retention. In this study two different SFSs have been examined to a total of ten (10) unknown vocabulary items. Both strategies provided morphosyntactic clarifications upon new contextualized vocabulary items. The traditional SFS (direct) provided the information only in one hypertext page with a selection on the relevant item. The experimental SFS (engaging) provided the exact same split information in three successive hypertext pages in the form of a hybrid dialogue asking from the subjects to move on to the next page by selecting the relevant link. It was hypothesized that this way the subjects would engage in their own learning process by actively asking for more information which would further lead to their better retention. The participants were fifty-two (52) foreign language learners (33 TD and 19 LD) aged from 9 to 12, attending an English language school at the level of A1 (CEFR). The design of the study followed a typical pre-post-post test procedure after an hour and after a week. The results indicated statistically significant group differences with TD children performing significantly better than the LD group in both short and long-term memory measurements and in both SFSs. As regards the effectiveness of one SFS over another the initial hypothesis was not supported by the evidence as the traditional SFS was more effective compared to the experimental one in both TD and LD children. This difference proved to be statistically significant only in the long-term memory measurement and only in the TD group. It may be concluded that the human brain seems to adapt to different SFS although it shows a small preference when information is provided in a direct manner.

Keywords: learning disabilities, memory, second/foreign language acquisition, supportive feedback

Procedia PDF Downloads 261

Authors: Ali Etemadi, Claudia Fernanda Yasar

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Elevated water storage tank structures (EWSTs) are high elevated-ponderous structural systems and very vulnerable to seismic vibrations. In past earthquake events, many of these structures exhibit poor performance and experienced severe damage. The dynamic analysis of the EWSTs under earthquake loads is, therefore, of significant importance for the design of the structure and a key issue for the development of modern methods, such as active control design. In this study, a reduced model of the EWSTs is explained, which is based on a tuned mass damper model (TMD). Vibration analysis of a structure under seismic excitation is presented and then used to propose an active vibration controller. MATLAB/Simulink is employed for dynamic analysis of the system and control of the seismic response. A single degree of freedom (SDOF) and two degree of freedom (2DOF) models of ELSTs are going to be used to study the concept of active vibration control. Lab-scale experimental models similar to pendulum are applied to suppress vibrations in ELST under seismic excitation. One of the most important phenomena in liquid storage tanks is the oscillation of fluid due to the movements of the tank body because of its base motions during an earthquake. Simulation results illustrate that the EWSTs vibration can be reduced by means of an input shaping technique that takes into account the dominant mode shape of the structure. Simulations with which to guide many of our designs are presented in detail. A simple and effective real-time control for seismic vibration damping can be, therefore, design and built-in practice.

Keywords: elevated water storage tank, tuned mass damper model, real time control, shaping control, seismic vibration control, the laplace transform

Procedia PDF Downloads 132

Authors: Atiwat Khatpibunchai, Taweesak Kritjaroen

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A social enterprise is the innovative hybrid organizations where its ultimate goal is to generate revenue and use it as a fund to solve the social and environmental problem. Although the evidence shows the clear value of economic, social and environmental aspects, the limitations of most of the social enterprises are the expanding impact of social and environmental aspects through the normal market mechanism. This is because the major sources of revenues of social enterprises derive from the business advocates who merely wish to support society and environment by using products and services of social enterprises rather than expect the satisfaction and the distinctive advantage of products and services. Thus, social enterprises cannot reach the achievement as other businesses do. The relevant concepts from the literature review revealed that dynamic capability is the ability to sense, integrate and reconfigure internal resources and utilize external resources to adapt to changing environments, create innovation and achieve competitive advantage. The objective of this research is to study the influence of dynamic capability that affects competitive advantage and sustainable performance, as well as to determine important elements of dynamic capability. The researchers developed a conceptual model from the related concepts and theories of dynamic capability. A conceptual model will support and show the influence of dynamic capability on competitive advantage and sustainable performance of social enterprises. The 230 organizations in South-East Asia served as participants in this study. The results of the study were analyzed by the structural equation model (SEM) and it was indicated that research model is consistent with empirical research. The results also demonstrated that dynamic capability has a direct and indirect influence on competitive advantage and sustainable performance. Moreover, it can be summarized that dynamic capability consists of the five elements: 1) the ability to sense an opportunity; 2) the ability to seize an opportunity; 3) the ability to integrate resources; 4) the ability to absorb resources; 5) the ability to create innovation. The study recommends that related sectors can use this study as a guideline to support and promote social enterprises. The focus should be pointed to the important elements of dynamic capability that are the development of the ability to transform existing resources in the organization and the ability to seize opportunity from changing market.

Keywords: dynamic capability, social enterprise, sustainable competitive advantage, sustainable performance

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Authors: Evgeniya Y. Yuzbasheva, Tigran V. Yuzbashev, Natalia I. Perkovskaya, Elizaveta B. Mostova

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Cell-surface display of lipase is of great interest as it has many applications in the field of biotechnology owing to its unique advantages: simplified product purification, and cost-effective downstream processing. One promising area of application for whole-cell biocatalysts with surface displayed lipase is biodiesel synthesis. Biodiesel is biodegradable, renewable, and nontoxic alternative fuel for diesel engines. Although the alkaline catalysis method has been widely used for biodiesel production, it has a number of limitations, such as rigorous feedstock specifications, complicated downstream processes, including removal of inorganic salts from the product, recovery of the salt-containing by-product glycerol, and treatment of alkaline wastewater. Enzymatic synthesis of biodiesel can overcome these drawbacks. In this study, Lip2p lipase was displayed on Yarrowia lipolytica cells via C- and N-terminal fusion variant. The active site of lipase is located near the C-terminus, therefore to prevent the activity loosing the insertion of glycine-serine linker between Lip2p and C-domains was performed. The hydrolytic activity of the displayed lipase reached 12,000–18,000 U/g of dry weight. However, leakage of enzyme from the cell wall was observed. In case of C-terminal fusion variant, the leakage was occurred due to the proteolytic cleavage within the linker peptide. In case of N-terminal fusion variant, the leaking enzyme was presented as three proteins, one of which corresponded to the whole hybrid protein. The calculated number of recombinant enzyme displayed on the cell surface is approximately 6–9 × 105 molecules per cell, which is close to the theoretical maximum (2 × 106 molecules/cell). Thus, we attribute the enzyme leakage to the limited space available on the cell surface. Nevertheless, cell-bound lipase exhibited greater stability to short-term and long-term temperature treatment than the native enzyme. It retained 74% of original activity at 60°C for 5 min of incubation, and 83% of original activity after incubation at 50°C during 5 h. Cell-bound lipase had also higher stability in organic solvents and detergents. The developed whole-cell biocatalyst was used for recycling biodiesel synthesis. Two repeated cycles of methanolysis yielded 84.1–% and 71.0–% methyl esters after 33–h and 45–h reactions, respectively.

Keywords: biodiesel, cell-surface display, lipase, whole-cell biocatalyst

Procedia PDF Downloads 463