Search results for: failure mode analysis

Authors: Madhavi-Priya Singh, Liam Lowe, Farouk Arnaout, Ludmilla Pillay, Giordan Perez, Luke Mischker, Steve Costa

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An Emergency Department consultant identified the failure of medical students to complete the task of clerking a patient in its entirety. As six medical students on our first clinical placement, we recognised our own failure and endeavoured to examine why this failure was consistent among all medical students that had been given this task, despite our best motivations as adult learner. Our aim is to understand and investigate the elements which impeded our ability to learn and perform as medical students in the clinical environment, with reference to the prescribed task. We also aim to generate a discussion around the delivery of medical education with potential solutions to these barriers. Six medical students gathered together to have a comprehensive reflective discussion to identify possible factors leading to the failure of the task. First, we thoroughly analysed the delivery of the instructions with reference to the literature to identify potential flaws. We then examined personal, social, ethical, and cultural factors which may have impacted our ability to complete the task in its entirety. Through collation of our shared experiences, with support from discussion in the field of medical education and ethics, we identified two major areas that impacted our ability to complete the set task. First, we experienced an ethical conflict where we believed the inconvenience and potential harm inflicted on patients did not justify the positive impact the patient interaction would have on our medical learning. Second, we identified a lack of confidence stemming from multiple factors, including the conflict between preclinical and clinical learning, perceptions of perfectionism in the culture of medicine, and the influence of upward social comparison. After discussions, we found that the various factors we identified exacerbated the fears and doubts we already had about our own abilities and that of the medical education system. This doubt led us to avoid completing certain aspects of the tasks that were prescribed and further reinforced our vulnerability and perceived incompetence. Exploration of philosophical theories identified the importance of the role of doubt in education. We propose the need for further discussion around incorporating both pedagogic and andragogic teaching styles in clinical medical education and the acceptance of doubt as a driver of our learning. Doubt will continue to permeate our thoughts and actions no matter what. The moral or psychological distress that arises from this is the key motivating factor for our avoidance of tasks. If we accept this doubt and education embraces this doubt, it will no longer linger in the shadows as a negative and restrictive emotion but fuel a brighter dialogue and positive learning experience, ultimately assisting us in achieving our full potential.

Keywords: medical education, clinical education, andragogy, pedagogy

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Authors: Ching-Sung Lee, Wei-Chou Hsu, Han-Yin Liu, Hung-Hsi Huang, Si-Fu Chen, Yun-Jung Yang, Bo-Chun Chiang, Yu-Chuang Chen, Shen-Tin Yang

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AlGaN/GaN high electron mobility transistors (HEMTs) have been intensively studied due to their intrinsic advantages of high breakdown electric field, high electron saturation velocity, and excellent chemical stability. They are also suitable for ultra-violet (UV) photodetection due to the corresponding wavelengths of GaN bandgap. To improve the optical responsivity by decreasing the dark current due to gate leakage problems and limited Schottky barrier heights in GaN-based HEMT devices, various metal-oxide-semiconductor HEMTs (MOS-HEMTs) have been devised by using atomic layer deposition (ALD), molecular beam epitaxy (MBE), metal-organic chemical vapor deposition (MOCVD), liquid phase deposition (LPD), and RF sputtering. The gate dielectrics include MgO, HfO2, Al2O3, La2O3, and TiO2. In order to provide complementary circuit operation, enhancement-mode (E-mode) devices have been lately studied using techniques of fluorine treatment, p-type capper, piezoneutralization layer, and MOS-gate structure. This work reports an Al2O3-dielectric Al0.25Ga0.75N/GaN E-mode MOS-HEMT design by using a cost-effective ozone water oxidization technique. The present ozone oxidization method advantages of low cost processing facility, processing simplicity, compatibility to device fabrication, and room-temperature operation under atmospheric pressure. It can further reduce the gate-to-channel distance and improve the transocnductance (gm) gain for a specific oxide thickness, since the formation of the Al2O3 will consume part of the AlGaN barrier at the same time. The epitaxial structure of the studied devices was grown by using the MOCVD technique. On a Si substrate, the layer structures include a 3.9 m C-doped GaN buffer, a 300 nm GaN channel layer, and a 5 nm Al0.25Ga0.75N barrier layer. Mesa etching was performed to provide electrical isolation by using an inductively coupled-plasma reactive ion etcher (ICP-RIE). Ti/Al/Au were thermally evaporated and annealed to form the source and drain ohmic contacts. The device was immersed into the H2O2 solution pumped with ozone gas generated by using an OW-K2 ozone generator. Ni/Au were deposited as the gate electrode to complete device fabrication of MOS-HEMT. The formed Al2O3 oxide thickness 7 nm and the remained AlGaN barrier thickness is 2 nm. A reference HEMT device has also been fabricated in comparison on the same epitaxial structure. The gate dimensions are 1.2 × 100 µm 2 with a source-to-drain spacing of 5 μm for both devices. The dielectric constant (k) of Al2O3 was characterized to be 9.2 by using C-V measurement. Reduced interface state density after oxidization has been verified by the low-frequency noise spectra, Hooge coefficients, and pulse I-V measurement. Improved device characteristics at temperatures of 300 K-450 K have been achieved for the present MOS-HEMT design. Consequently, Al2O3-dielectric Al0.25Ga0.75N/GaN E-mode MOS-HEMTs by using the ozone water oxidization method are reported. In comparison with a conventional Schottky-gate HEMT, the MOS-HEMT design has demonstrated excellent enhancements of 138% (176%) in gm, max, 118% (139%) in IDS, max, 53% (62%) in BVGD, 3 (2)-order reduction in IG leakage at VGD = -60 V at 300 (450) K. This work is promising for millimeter-wave integrated circuit (MMIC) and three-terminal active UV photodetector applications.

Keywords: MOS-HEMT, enhancement mode, AlGaN/GaN, passivation, ozone water oxidation, gate leakage

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Authors: Mohamad Amin Amini, Mehdi Poursha

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Nonlinear response history analysis (NL-RHA) is a robust analytical tool for estimating the seismic demands of structures responding in the inelastic range. However, because of its conceptual and numerical complications, the nonlinear static procedure (NSP) is being increasingly used as a suitable tool for seismic performance evaluation of structures. The conventional pushover analysis methods presented in various codes (FEMA 356; Eurocode-8; ATC-40), are limited to the first-mode-dominated structures, and cannot take higher modes effect into consideration. Therefore, since more than a decade ago, researchers developed enhanced pushover analysis procedures to take higher modes effect into account. The main objective of this study is to propose an enhanced invariant lateral displacement distribution to take higher modes effect into consideration in performing a displacement-based pushover analysis, whereby a set of laterally applied displacements, rather than forces, is monotonically applied to the structure. For this purpose, the effect of different parameters such as the spectral displacement of ground motion, the modal participation factor, and the effective modal participating mass ratio on the lateral displacement distribution is investigated to find the best distribution. The major simplification of this procedure is that the effect of higher modes is concentrated into a single invariant lateral load distribution. Therefore, only one pushover analysis is sufficient without any need to utilize a modal combination rule for combining the responses. The invariant lateral displacement distribution for pushover analysis is then calculated by combining the modal story displacements using the modal combination rules. The seismic demands resulting from the different procedures are compared to those from the more accurate nonlinear response history analysis (NL-RHA) as a benchmark solution. Two structures of different heights including 10 and 20-story special steel moment resisting frames (MRFs) were selected and evaluated. Twenty ground motion records were used to conduct the NL-RHA. The results show that more accurate responses can be obtained in comparison with the conventional lateral loads when the enhanced modal lateral displacement distributions are used.

Keywords: displacement-based pushover, enhanced lateral load distribution, higher modes effect, nonlinear response history analysis (NL-RHA)

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Authors: Rashid Masoud Ali Al-Mazrui, Ramadhani Mashaka Shabani

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Islamic banks and financial institutions are exposed to the same risks as conventional banking. These risks include the rate return risk, credit or market risk, liquidity risk, and operational risk among others. However, being a financial institution that operates Islamic banking and finance operations, there is additional risk associated with its operations different from conventional finance, such as displacing commercial risk. They face Shari'ah compliance risks because of their failure to follow Shari'ah principles. To have proper mitigation and risk management, banks should have proper risk management policies to mitigate risks. This paper aims to study the risk management taken by Islamic banks in comparison with conventional banks. Also, the study evaluates the provisions for risk management taken by selected Islamic banks and conventional banks. The study employs qualitative analysis using secondary data by applying a content analysis approach with a sample size of 4 Islamic banks and four conventional banks ranging from 2010 to 2020. We find that these banks all use the same technique, except for the associated risk. The extra ways are used, but only for additional risks that are available to Islamic banking and finance.

Keywords: emerging risk, risk management, Islamic banking, conventional bank

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Authors: Hernán A. Perez, Luis J. Armando, Néstor H. García

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Background and aims Cardiovascular disease rates are very high in patients with renal failure (CRF), but the underlying mechanisms are incompletely understood. Traditional cardiovascular risk factors do not explain the increased risk, and observational studies have observed paradoxical or absent associations between classical risk factors and mortality in dialysis patients. A large randomized controlled trial, the 4D Study, the AURORA and the ALERT study found that statin therapy in CRF do not reduce cardiovascular events. These results may be the results of ‘accelerated atherosclerosis’ observed on these patients. The objective of this study was to investigate if carotid total plaque area (TPA), a measure of carotid plaque burden growth is increased at progressively lower creatinine clearance in patients with CRF. We studied a cohort of patients with CRF not on dialysis, reasoning that risk factor associations might be more easily discerned before end stage renal disease. Methods: The Blossom DMO Argentina ethics committee approved the study and informed consent from each participant was obtained. We performed a cohort study in 412 patients with Stage 1, 2 and 3 CRF. Clinical and laboratory data were obtained. TPA was determined using bilateral carotid ultrasonography. Modification of Diet in Renal Disease estimation formula was used to determine renal function. ANOVA was used when appropriate. Results: Stage 1 CRF group (n= 16, 43±2yo) had a blood pressure of 123±2/78±2 mmHg, BMI 30±1, LDL col 145±10 mg/dl, HbA1c 5.8±0.4% and had the lowest TPA 25.8±6.9 mm2. Stage 2 CRF (n=231, 50±1 yo) had a blood pressure of 132±1/81±1 mmHg, LDL col 125±2 mg/dl, HbA1c 6±0.1% and TPA 48±10mm2 ( p< 0.05 vs CRF stage 1) while Stage 3 CRF (n=165, 59±1 yo) had a blood pressure of 134±1/81±1, LDL col 125±3 mg/dl, HbA1c 6±0.1% and TPA 71±6mm2 (p < 0.05 vs CRF stage 1 and 2). Conclusion: Our data indicate that TPA increases along the renal function deterioration, and it is not related with the LDL cholesterol and triglycerides levels. We suggest that mechanisms other than the classics are responsible for the observed excess of cardiovascular disease in CKD patients and finally, determination of total plaque area should be used to measure effects of antiatherosclerotic therapy.

Keywords: hypertension, chronic renal failure, atherosclerosis, cholesterol

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Authors: Mahan Qwamizadeh, Kun Zhou, Zuoqi Zhang, Yong Wei Zhang

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Typical load-bearing biological materials like bone, mineralized tendon and shell, are biocomposites made from both organic (collagen) and inorganic (biomineral) materials. This amazing class of materials with intrinsic internally designed hierarchical structures show superior mechanical properties with regard to their weak components from which they are formed. Extensive investigations concentrating on static loading conditions have been done to study the biological materials failure. However, most of the damage and failure mechanisms in load-bearing biological materials will occur whenever their structures are exposed to dynamic loading conditions. The main question needed to be answered here is: What is the relation between the layout and architecture of the load-bearing biological materials and their dynamic behavior? In this work, a staggered model has been developed based on the structure of natural materials at nanoscale and Finite Element Analysis (FEA) has been used to study the dynamic behavior of the structure of load-bearing biological materials to answer why the staggered arrangement has been selected by nature to make the nanocomposite structure of most of the biological materials. The results showed that the staggered structures will efficiently attenuate the stress wave rather than the layered structure. Furthermore, such staggered architecture is effectively in charge of utilizing the capacity of the biostructure to resist both normal and shear loads. In this work, the geometrical parameters of the model like the thickness and aspect ratio of the mineral inclusions selected from the typical range of the experimentally observed feature sizes and layout dimensions of the biological materials such as bone and mineralized tendon. Furthermore, the numerical results validated with existing theoretical solutions. Findings of the present work emphasize on the significant effects of dynamic behavior on the natural evolution of load-bearing biological materials and can help scientists to design bioinspired materials in the laboratories.

Keywords: load-bearing biological materials, nanostructure, staggered structure, stress wave decay

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Authors: Mohanad Alhabo, Naveed Nawaz

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The ongoing call or data session must be maintained to ensure a good quality of service. This can be accomplished by performing the handover procedure while the user is on the move. However, the dense deployment of small cells in 5G networks is a challenging issue due to the extensive number of handovers. In this paper, a neighbour cell list method is proposed to reduce the number of target small cells and hence minimizing the number of handovers. The neighbour cell list is built by omitting cells that could cause an unnecessary handover and handover failure because of short time of stay of the user in these cells. A multi-attribute decision making technique, simple additive weighting, is then applied to the optimized neighbour cell list. Multi-tier small cells network is considered in this work. The performance of the proposed method is analysed and compared with that of the existing methods. Results disclose that our method has decreased the candidate small cell list, unnecessary handovers, handover failure, and short time of stay cells compared to the competitive method.

Keywords: handover, HetNets, multi-attribute decision making, small cells

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Authors: Hung-Yuan Chang, Wen-Lung Chiang, Kuo-Liang Wu, Chen-Tsung Lin

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National Space Organization (NSPO) has completed in 2014 the development of a space-borne GPS receiver, including design, manufacture, comprehensive functional test, environmental qualification test and so on. The main performance of this receiver include 8-meter positioning accuracy, 0.05 m/sec speed-accuracy, the longest 90 seconds of cold start time, and up to 15g high dynamic scenario. The receiver will be integrated in the autonomous FORMOSAT-7 NSPO-Built satellite scheduled to be launched in 2019 to execute pre-defined scientific missions. The flight model of this receiver manufactured in early 2015 will pass comprehensive functional tests and environmental acceptance tests, etc., which are expected to be completed by the end of 2015. The space-borne GPS receiver is a pure software design in which all GPS baseband signal processing are executed by a digital signal processor (DSP), currently only 50% of its throughput being used. In response to the booming global navigation satellite systems, NSPO will gradually expand this receiver to become a multi-mode, multi-band, high-precision navigation receiver, and even a science payload, such as the reflectometry receiver of a global navigation satellite system. The fundamental purpose of this extension study is to port some software algorithms such as signal acquisition and correlation, reused code and large amount of computation load to the FPGA whose processor is responsible for operational control, navigation solution, and orbit propagation and so on. Due to the development and evolution of the FPGA is pretty fast, the new system architecture upgraded via an FPGA should be able to achieve the goal of being a multi-mode, multi-band high-precision navigation receiver, or scientific receiver. Finally, the results of tests show that the new system architecture not only retains the original overall performance, but also sets aside more resources available for future expansion possibility. This paper will explain the detailed DSP/FPGA architecture, development, test results, and the goals of next development stage of this receiver.

Keywords: space-borne, GPS receiver, DSP, FPGA, multi-mode multi-band

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Authors: Lee Tasker, Ali Karrech, Jeffrey Shragge, Matthew Josh

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Monitoring for the deterioration of concrete infrastructure is an important assessment tool for an engineer and difficulties can be experienced with monitoring for deterioration within an infrastructure. If a failure crack, or fluid seepage through such a crack, is observed from the surface often the source location of the deterioration is not known. Geophysical methods are used to assist engineers with assessing the subsurface conditions of materials. Techniques such as Ground Penetrating Radar (GPR) provide information on the location of buried infrastructure such as pipes and conduits, positions of reinforcements within concrete blocks, and regions of voids/cavities behind tunnel lining. This experiment underlines the application of GPR as an infrastructure-monitoring tool to highlight and monitor regions of possible deterioration within a concrete test wall due to an increase in the generation of fractures; in particular, during a time period of applied load to a concrete wall up to and including structural failure. A three-point load was applied to a concrete test wall of dimensions 1700 x 600 x 300 mm³ in increments of 10 kN, until the wall structurally failed at 107.6 kN. At each increment of applied load, the load was kept constant and the wall was scanned using GPR along profile lines across the wall surface. The measured radar amplitude responses of the GPR profiles, at each applied load interval, were reconstructed into depth-slice grids and presented at fixed depth-slice intervals. The corresponding depth-slices were subtracted from each data set to compare the radar amplitude response between datasets and monitor for changes in the radar amplitude response. At lower values of applied load (i.e., 0-60 kN), few changes were observed in the difference of radar amplitude responses between data sets. At higher values of applied load (i.e., 100 kN), closer to structural failure, larger differences in radar amplitude response between data sets were highlighted in the GPR data; up to 300% increase in radar amplitude response at some locations between the 0 kN and 100 kN radar datasets. Distinct regions were observed in the 100 kN difference dataset (i.e., 100 kN-0 kN) close to the location of the final failure crack. The key regions observed were a conical feature located between approximately 3.0-12.0 cm depth from surface and a vertical linear feature located approximately 12.1-21.0 cm depth from surface. These key regions have been interpreted as locations exhibiting an increased change in pore-space due to increased mechanical loading, or locations displaying an increase in volume of micro-cracks, or locations showing the development of a larger macro-crack. The experiment showed that GPR is a useful geophysical monitoring tool to assist engineers with highlighting and monitoring regions of large changes of radar amplitude response that may be associated with locations of significant internal structural change (e.g. crack development). GPR is a non-destructive technique that is fast to deploy in a production setting. GPR can assist with reducing risk and costs in future infrastructure maintenance programs by highlighting and monitoring locations within the structure exhibiting large changes in radar amplitude over calendar-time.

Keywords: 4D GPR, engineering geophysics, ground penetrating radar, infrastructure monitoring

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Authors: Chiung-Yao Huang, Yu-Cheng Lin, Chiung-Hui Chen

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This study seeks to examine perceived environmental corporate social responsibility (ECSR) with a focus on negative environmental questions, related to intention of ethical investment intention after a environmental failure recovery. An empirical test was employed to test the hypotheses. We manipulated the information on negative ECSR activities of a hypothetical firm in a experimental design with a failure recovery treatment. The company’s negative ECSR recovery was depicted in a positive perspective (depicting a follow-up strong social action), whereas in the negative ECSR treatment it was described in a negative perspective (depicting a follow-up non social action). In both treatments, information about other key characteristics of the focal company were kept constant. Investors’ intentions to invest in the company’s stock were evaluated by multi-item scales. Results indicate that positive ECSR recovery information about a firm enhances investors’ intentions to invest in the company’s stock. In addition, perceived moral intensity has a significant impact on the intention of ethical investment and that perceived moral intensity also serves as a key moderating variable in the relationship between negative ECSR and the intention of ethical investment. Finally, theoretical and managerial implications of the findings are discussed. Practical implications: The results suggest that managers may need to be aware of perceived moral intensity as a key variable in restoring the intention of ethical investment. The results further suggest that perceived moral intensity has a direct, and it also has an moderating influence between ECSR and the intention of ethical investment. Originality/value: In an attempt to deepen the understanding of how investors perceptions of firm environmental CSR are connected with other investor‐related outcomes through ECSR recovery, the present research proposes a comprehensive model which encompasses ECSR and other key relationship constructs after a ECSR failure and recovery.

Keywords: ethical investment, Environmental Corporate Social Responsibility(ECSR), ECSR recovery, moral intensity

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Authors: Muhammad Ganda Wiratama

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XYZ company is one of the upstream chemical companies that produce chemical products such as NaOH, HCl, NaClO, VCM, EDC, and PVC for downstream companies. The products are shipped by land using trucks and sea lanes using ship mode. Especially for solid products such as flake caustic soda (F-NaOH) and PVC resin, the products are sold in loose bag packing and palletize packing (packed in pallet). The focus of this study is to increase the number of items that can be loaded in pallet packaging on the company's logistics vehicle. This is very difficult because on this packaging, the dimensions or size of the material to be loaded become larger and certainly much heavier than the loose bag packing. This factor causes the arrangement and handling of materials in the mode of transportation more difficult. In this case, it is difficult to load a different type of volume packing pallet dimension in one truck or container. By using the Cube-IQ software, it is hoped that the planning of stuffing activity material by pallet can become easier in optimizing the existing space with various possible combinations of possibilities. In addition, the output of this software can also be used as a reference for operators in the material handling include the order and orientation of materials contained in the truck or container. The more optimal contents of logistics cargo, then transportation costs can also be minimized.

Keywords: loading activity, container loading, palletize product, simulation

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Authors: K. S. Sivakumaran, Bo Chen

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The floor beams of steel buildings, cold-formed steel floor joists, in particular, often require large web openings, which may affect their shear capacities. A cost effective way to mitigate the detrimental effects of such openings is to weld/fasten reinforcements. A difficulty associated with an experimental investigation to establish suitable reinforcement schemes for openings in shear zone is that moment always coexists with the shear, and thus, it is impossible to create pure shear state in experiments, resulting in moment influenced results. However, finite element analysis can be conveniently used to investigate the pure shear behaviour of webs including webs with reinforced opening. This paper presents that the details associated with the finite element analysis of thick/thin-plates (representing the web of hot-rolled steel beam, and the web of a cold-formed steel member) having a large reinforced openings. The study considered thin simply supported rectangular plates subjected to inplane shear loadings until failure (including post-buckling behaviour). The plate was modelled using geometrically non-linear quadrilateral shell elements, and non-linear stress-strain relationship based on experiments. Total Lagrangian (TL) with large displacement/small strain formulation was used for such analysis. The model also considered the initial geometric imperfections. This study considered three reinforcement schemes, namely, flat, lip, and angle reinforcements. This paper discusses the modelling considerations and presents the results associated with the various reinforcement schemes under consideration. The paper briefly compares the analysis results with the experimental results.

Keywords: cold-formed steel, finite element analysis, opening, reinforcement, shear resistance

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Authors: Soheib Fergani

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This paper concerns with the formal asymptotic stability guarantees, analysis and evaluation of a nonlinear controlled unmanned aerial vehicles (uav) for trajectory tracking purpose. As the system has been recognised as an under-actuated non linear system, the control strategy has been oriented towards a hierarchical control. The dynamics of the system and the mission purpose make it mandatory to provide an absolute proof of the vehicle stability during the maneuvers. For this sake, this work establishes the complete theoretical proof for an implementable control oriented strategy that asymptotically stabilizes (GAS and LISS) the system and has never been provided in previous works. The considered model is reorganized into two partly decoupled sub-systems. The concidered control strategy is presented into two stages: the first sub-system is controlled by a nonlinear backstepping controller that generates the desired control inputs to stabilize the second sub-system. This methodology is then applied to a harware in the loop uav simulator (SiMoDrones) that reproduces the realistic behaviour of the uav in an indoor environment has been performed to show the efficiency of the proposed strategy.

Keywords: UAV application, trajectory tracking, backstepping, sliding mode control, input to state stability, stability evaluation

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Authors: Sumanta Das, Miroslav Gašparík, Tomáš Kytka, Anil Kumar Sethy

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In this modern century, Cross-laminated timber (CLT) evolved as an excellent material for building and high load-bearing structural applications worldwide. CLT is produced mainly from softwoods such as Norway spruce, White fir, Scots pine, European larch, Douglas fir, and Swiss stone pine. The use of hardwoods in CLT production is still at an early stage, and the utilization of hardwoods is expected to provide the opportunity for obtaining higher bending stiffness and shear resistance to CLT panels. In load-bearing structures like CLT, bonding is an important character that is needed to evaluate. One particular issue with using hardwood lumber in CLT panels is that it is often more challenging to achieve a strong, durable adhesive bond. Several researches in the past years have already evaluated the bonding properties of CLT panels from hardwood both from higher and lower densities. This research aims to identify the effect of pressure and glue spread and evaluate which poplar lumber characteristics affect adhesive bond quality. Three-layered CLT panels were prepared from poplar wood with one-component polyurethane (PUR) adhesive by applying pressure of 0.6 N/mm2 and 1 N/mm2 with a glue spread rate of 160 and 180 g/m2. The delamination and block shear tests were carried out as per EN 16351:2015, and the wood failure percentage was also evaluated. The results revealed that glue spread rate and applied pressure significantly influenced both the shear bond strength and wood failure percentage of the CLT. However, samples with lower pressure 0.6 N/mm2 and less glue spread rate showed delamination, and in samples with higher pressure 1 N/mm2 and higher glue spread rate, no delamination was observed. All the properties determined by this study met the minimum requirement mentioned in EN 16351:2015 standard.

Keywords: cross-laminated timber, delamination, glue spread rate, poplar, pressure, PUR, shear strength, wood failure percentage

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Authors: Tomotaka Aoki, Isao Tomita

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We examined the on-off ratio and frequency components of output signals from an electron-interference device made of GaAs/AlₓGa₁₋ₓAs by solving the time-dependent Schrödinger's equation on conducting electrons in the channel waveguide of the device. For electron-wave modulation, a periodic voltage of frequency f was applied to the channel. Furthermore, we examined the voltage-amplitude dependence of the signals in time and frequency domains and found that large applied voltage deformed the output-signal waveform and created additional side modes (frequencies) near the modulation frequency f and that there was a trade-off between on-off ratio and side-mode creation.

Keywords: electrical conduction, electron interference, frequency spectrum, on-off ratio

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Authors: Jatuporn Juyjingam, Pitak Siriwong

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This paper presents a study of factors effecting the success and failure of social enterprise in Thailand identifying communication as one of the criteria for measuring the social impact of social enterprise. The study focused on the communication driver of the SCALERS model. The research examines how communication is viewed in Thailand social enterprise. The research aims to determine how selected social enterprise uses communication in their operations. More specifically, the study aims to 1) describe the profile of social enterprise in Thailand, 2) identify the different roles of communication in the operation of social enterprise in Thailand, 3) determine Thailand social enterprise concept of communication. The study made use of the case study and cross case study research designs. For the profiling of the social enterprises, the case study was used. The researchers made use of the cross-case research design in identifying trends across the ten social enterprises and in determining the social entrepreneurs’ concept of communication. Key informant interviews were conducted with the heads or representatives of selected social enterprises, a three-part interview schedule was used to facilitate data gathering. The three parts included are 1) Profile of social enterprise in Thailand 2) How social enterprises apply communication in their operations 3) What is the key success in using communication among social enterprise in Thailand. This study is an exploratory research.

Keywords: communication, social entrepreneurship, social enterprise, sustainability development

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Authors: V. Revathi, J. Thaarrini, M. Venkob Rao

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This paper presents a study on use of alkali activated bottom ash (BA) and ground granulated blast furnace slag (GGBS) blend in paver blocks. A preliminary effort on alkali-activated bottom ash, blast furnace slag based geopolymer (BA-GGBS-GP) mortar with river sand was carried out to identify the suitable mix for paver block. Several mixes were proposed based on the combination of BA-GGBS. The percentage ratio of BA:GGBS was selected as 100:0, 75:25, 50:50, 25:75 and 0:100 for the source material. Sodium based alkaline activators were used for activation. The molarity of NaOH was considered as 8M. The molar ratio of SiO2 to Na2O was varied from 1 to 4. Two curing mode such as ambient and steam curing 60°C for 24 hours were selected. The properties of paver block such as compressive strength split tensile strength, flexural strength and water absorption were evaluated as per IS15658:2006. Based on the preliminary study on BA-GGBS-GP mortar, the combinations of 25% BA with 75% GGBS mix for M30 and 75% BA with 25% GGBS mix for M35 grade were identified for paver block. Test results shows that the combination of BA-GGBS geopolymer paver blocks attained remarkable compressive strength under steam curing as well as in ambient mode at 3 days. It is noteworthy to know BA-GGBS-GP has promising future in the construction industry.

Keywords: bottom ash, GGBS, alkali activation, paver block

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Authors: Taghreed Al-Khalid, Muftah El-Naas

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As an economical and environmentally friendly technology, biological treatment has been shown to be one of the most promising approaches for the removal of numerous types of organic water pollutants such as Chlorophenols, which are hazardous pollutants commonly encountered in wastewater generated by the petroleum and petrochemical industries. This study aimed at evaluating the performance of a spouted bed bioreactor (SBBR) for aerobic biodegradation of 2, 4 dichlorophenol (DCP) by a commercial strain of Pseudomonas putida immobilized in polyvinyl alcohol (PVA) gel particles. The SBBR is characterized by systematic intense mixing, resulting in improvement of the biodegradation rates through reducing the mass transfer limitations. The reactor was evaluated in both batch and continuous mode in order to evaluate its hydrodynamics in terms of stability and response to shock loads. The SBBR was able to maintain a stable operation and recovered quickly to its normal operating mode once the shock load had been removed. In comparison to a packed bed reactor bioreactor, the SBBR proved to be more efficient and more stable, achieving a removal percentage and throughput of 80% and 1414 g/m3day, respectively. In addition, the biodegradation of chlorophenols was mathematically modeled using a dynamic modeling approach in order to assess reaction and mass transfer limitations. The results confirmed the effectiveness of the use of the PVA immobilization technique for the biodegradation of phenols.

Keywords: biodegradation, 2, 4 dichlorophenol, immobilization, polyvinyl alcohol (PVA) gel

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Authors: Nikhil A. Gavhane, Sachin Shah, Ishant S. Mahajan, Pawan D. Bahekar

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Introduction: Millions of people are affected with dengue fever every year, which drives up healthcare expenses in many low-income countries. Organ failure and other serious symptoms may result. Another worldwide public health problem is sickle cell anaemia, which is most prevalent in Africa, the Caribbean, and Europe. Dengue epidemics have reportedly occurred in locations with a high frequency of sickle cell disease, compounding the health problems in these areas. Aims and Objectives: This study examines dengue infection in sickle cell disease-afflicted pre-schoolers. Method:This Retrospective cohort study examined paediatric patients. Young people with sickle cell disease (SCD), dengue infection, and a control group without SCD or dengue were studied. Data on demographics, SCD consequences, medical treatments, and laboratory findings were gathered to analyse the influence of SCD on dengue severity and clinical outcomes, classified as severe or non-severe by the 2009 WHO classification. Using fever or admission symptoms, the research estimated acute illness duration. Result: Table 1 compares haemoglobin genotype-based dengue episode features in SS, SC, and controls. Table 2 shows that severe dengue cases are older, have longer admission delays, and have particular symptoms. Table 3's multivariate analysis indicates SS genotype's high connection with severe dengue, multiorgan failure, and acute pulmonary problems. Table 4 relates severe dengue to greater white blood cell counts, anaemia, liver enzymes, and reduced lactate dehydrogenase. Conclusion: This study is valuable but confined to hospitalised dengue patients with sickle cell illness. Small cohorts limit comparisons. Further study is needed since findings contradict predictions.

Keywords: dengue, chills, headache, severe myalgia, vomiting, nausea, prostration

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Authors: Mohammad H. Ruhipour, Mahdi Goharrokhi, Mahsa Ghasemi, Artadokht Ostadsarayi

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In this paper, we are aiming to study the consequences of chlorine gas leak in direct chlorine gas injection compared to using bleach (sodium hypochlorite), studying the negative effects both on the environment and individuals. This study was performed in the cooling towers of a natural fractioning unit of Bandar-e-IMAM petrochemical plant. Considering that chlorine gas is highly toxic and based on the health regulation, its release into the surrounding environment can be very dangerous for people and even fatal for individuals. We studied performing quantitative studies in the worst cases of event incidence. In addition, studying alternative methods with a lower risk was also on the agenda to select the least likely possible option causing an accident. In this paper chlorine gas release consequences have been evaluated by using PHAST software. Reaching to 10 ppm of chlorine gas concentration was basis of hazardous area determination. The results show that the full chlorine gas line rupture scenario in Pasquill category F, were worst case, and many people could be harmed around cooling towers area because of chlorine gas inhalation.

Keywords: chlorine gas, consequence modeling, cooling towers, direct chlorination, risk assessment, system failure

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Authors: Sorour Semsari Parapari, Mehmet Ali Gülgün, Melih Papila

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Cement production is one of the most energy-intensive processes consuming a high amount of thermal energy. Nowadays, alternative fuels are being used in cement manufacturing in a large scale as a help to provide the necessary energy. The alternative fuels could consist of any disposal like waste plastics, used tires and biomass. It has been suggested that the clinker properties might be affected by using these fuels because of foreign elements incorporation to the composition. Studying the distribution of clinker phases and their chemical composition is possible with scanning electron microscopy (SEM). In this study, clinker samples were produced using different alternative fuels in cement firing kilns. The microstructural observations by back-scattered electrons (BSE) mode in SEM (JEOL JSM-6010LV) showed that the clinker phase distribution was dissimilar in samples prepared with different alternative fuels. The alite to belite (a/b) phase content of samples was quantified by image analysis. The results showed that the a/b varied between 5.2 and 1.5 among samples as the average value for six clinker nodules. The elemental analysis by energy-dispersive x-ray spectroscopy (EDS) mounted on SEM indicated the variation in chemical composition among samples. Higher amounts of sulfur and alkalis seemed to reduce the alite phase formation in clinkers.

Keywords: alternative fuels, cement clinker, microstructure, SEM

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Authors: Dmitriy V. Chulkov

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Escalation of commitment is defined as continuation of a project after receiving negative information about it. While literature in management and psychology identified various factors contributing to escalation behavior, this phenomenon has received little analysis in economics, potentially due to the apparent irrationality of escalation. In this study, we present an economic model of escalation with asymmetric information in a principal-agent setup where the agents are responsible for a project selection decision and discover the outcome of the project before the principal. Our theoretical model complements the existing literature on several accounts. First, we link the incentive to escalate commitment to a project with the turnover decision by the manager. When a manager learns the outcome of the project and stops it that reveals that a mistake was made. There is an incentive to continue failing projects and avoid admitting the mistake. This incentive is enhanced when the agent may voluntarily resign from the firm before the outcome of the failing project is revealed, and thus not bear the full extent of reputation damage due to project failure. As long as some successful managers leave the firm for extraneous reasons, outside firms find it difficult to link failing projects with certainty to managers that left a firm. Second, we demonstrate that non-CEO managers have reputation concerns separate from those of the CEO, and thus may escalate commitment to projects they oversee, when such escalation can attenuate damage to reputation from impending project failure. Such incentive for escalation will be present for non-CEO managers if the CEO delegates responsibility for a project to a non-CEO executive. If reputation matters for promotion to the CEO, the incentive for a rising executive to escalate in order to protect reputation is distinct from that of a CEO. Third, our theoretical model is supported by empirical analysis of changes in the firm’s operations measured by the presence of discontinued operations at the time of turnover among the top four members of the top management team. Discontinued operations are indicative of termination of failing projects at a firm. The empirical results demonstrate that in a large dataset of over three thousand publicly traded U.S. firms for a period from 1993 to 2014 turnover by top executives significantly increases the likelihood that the firm discontinues operations. Furthermore, the type of turnover matters as this effect is strongest when at least one non-CEO member of the top management team leaves the firm and when the CEO departure is due to a voluntary resignation and not to a retirement or illness. Empirical results are consistent with the predictions of the theoretical model and suggest that escalation of commitment is primarily observed in decisions by non-CEO members of the top management team.

Keywords: discontinued operations, escalation of commitment, executive turnover, top management teams

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Authors: Athena Nguyen, Rojin Belganeh

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In recycling plastics industries, waste plastics are converted into monomers and other useful molecules by chemical reactions. Thermal energy generated by incineration is recovered when waste plastics melt. During the process, Flame retardants containing products get in, and brominated flame retardants (BFRs) are often used to reduce the flammability of products. Some of the originally formulated brominated flame retardants additives are restricted by the RoHS Directive, such as PBDE and PBB. The determination of BFRs other than those restricted by the RoHS directive is required. Frontier Lab developed a pyrolyzer based on the vertical micro-furnace design. The multi-mode pyrolyzer with different modes of operations, including evolve gas analysis (EGA), flash pyrolysis, thermal desorption, heart cutting, allows users to choose among the techniques for their analysis purposes. The method requires very little sample preparation. The first step is to perform an EGA using temperature programs. This technique provides information about the thermal temperature behaviors of the sample. The EGA thermogram is then used to determine the next steps in the analysis process. In this presentation, with an Optimal thermal temperature zone identified based on EGA thermogram, thermal desorption GC/MS is a chosen technique for the determination of brominated flame retardants in recycled plastic toys. Five types of general-purpose brominated flame retardants other than those restricted by the RoHS Directive are determined by the standard addition method.

Keywords: gas chromatography/mass spectrometry, pyrolysis, pyrolyzer, thermal desorption-GC/MS

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Authors: Maithem Al-Saadi, Min An

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During airport planning and design stages, the major issues of capacity and safety in construction and operation of an airport need to be taken into consideration. The airside of an airport is a major and critical infrastructure that usually consists of runway(s), taxiway system, and apron(s) etc., which have to be designed according to the international standards and recommendations, and local limitations to accommodate the forecasted demands. However, in many cases, airport airsides are suffering from unexpected risks that occurred during airport operations. Therefore, safety risk assessment should be applied in the planning and design of airsides to cope with the probability of risks and their consequences, and to make decisions to reduce the risks to as low as reasonably practicable (ALARP) based on safety risk assessment. This paper presents a combination approach of Failure Modes, Effect, and Criticality Analysis (FMECA), Fuzzy Reasoning Approach (FRA), and Fuzzy Analytic Hierarchy Process (FAHP) to develop a risk analysis model for safety risk assessment. An illustrated example is used to the demonstrate risk assessment process on how the design of an airside in an airport can be analysed by using the proposed safety design risk assessment model.

Keywords: airport airside planning and design, design for safety, fuzzy reasoning approach, fuzzy AHP, risk assessment

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Authors: Brandtner-Hafner Martin

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Adhesives are increasingly being used in the construction sector. On the one hand, this concerns dowel reinforcements using chemical anchors. On the other hand, the sealing and repair of cracks in structural concrete components are still on the rise. In the field of bonding, the interface between the joined materials is the most critical area. Therefore, it is of immense importance to characterize and investigate this section sufficiently by fracture analysis. Since standardized mechanical test methods are not sufficiently capable of doing this, recourse is made to an innovative concept based on fracture energy. Therefore, a series of experimental tests were performed using the so-called GF-principle to study the interface bonding safety of adhesively bonded concrete joints. Several different structural adhesive systems based on epoxy, CA/A hybrid, PUR, MS polymer, dispersion, and acrylate were selected for bonding concrete substrates. The results show that stable crack propagation and prevention of uncontrolled failure in bonded concrete joints depend very much on the adhesive system used, and only fracture analytical evaluation methods can provide empirical information on this.

Keywords: interface bonding safety, adhesively bonded concrete joints, GF-principle, fracture analysis

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Authors: Kenneth Christie

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Syria and Iraq are Arabian nightmares at the local, the regional and global levels in terms of human security and the protection of the vulnerable. Wracked by civil war, ethnic and political violence in the last 5 years in the case of Syria and 13 years in the case of Iraq, the body count now is staggering; the humanitarian crisis continues and there appears no end to this. A crisis that has claimed the lives of 200,000 people so far in Syria, sparked a humanitarian catastrophe fuelled violent Islamic extremism and exposed serious splits in the international community who appear to have no consensus. The international community’s failure to act is simply another sign of the desperate situation which has developed over conflicts that appears unsolvable in the immediate future and may be intractable in the long range. Three things are really at stake I’m going to argue in these continuing crises and how it will affect the human security dimensions of the conflict. Firstly, the protection of vulnerable individuals and civilians in the war, 2ndly, the dire consequences for regional instability as a result and thirdly the risks for minority and ethnic identities who are caught up in this, within and across these volatile borders. This paper will examine these elements and the consequences of the conflict in terms of human security, migration and development.

Keywords: human security, migration, Syria and Iraq, conflict and development

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Authors: Francesco Pisano

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Islam has been an important topic in Turkey’s institutional identity. Since the dawn of the Turkish Republic, at the end of the First World War, the new Turkish leadership was urged to deal with the religious heritage of the Sultanate. Mustafa Kemal Ataturk, Turkey’s first President, led the country in a process of internal change, substantially modifying not merely the democratic stance of it, but also the way politics was addressing the Muslim faith. Islam was banned from the public sector of the society and was drastically marginalized to the mere private sphere of citizens’ lives. Headscarves were banned from institutional buildings together with any other religious practice, while the country was proceeding down a path of secularism and Westernization. This issue is demonstrated by the fact that even a new elected Prime Minister, Recep Tayyip Erdoğan, was initially barred from taking the institutional position, because of allegations that he had read a religious text while campaigning. Over the years, thanks to this initial internal shift, Turkey has often been seen by Western partners as one of the few countries that had managed to find a perfect balance between a democratic stance and an Islamic inherent nature. In the early 2000s, this led many academics to believe that Ankara could eventually have become the next European capital. Since then, the internal and external landscape of Turkey has drastically changed. Today, religion has returned to be an important point of reference for Turkish politics, considering also the failure of the European negotiations and the always more unstable external environment of the country. This paper wants to address this issue, looking at the important role religion has covered in the Turkish society and the way it has been politicized since the early years of the Republic. It will evolve from a more theoretical debate on secularism and the path of political westernization of Turkey under Ataturk’s rule to a more practical analysis of today’s situation, passing through the failure of Ankara’s accession into the EU and the current tense political relation with its traditional NATO allies. The final objective of this research, therefore, is not to offer a meticulous opinion on Turkey’s current international stance. This issue will be left entirely to the personal consideration of the reader. Rather, it will supplement the existing literature with a comprehensive and more structured analysis on the role Islam has played on Turkish politics since the early 1920s up until the political domestic revolution of the early 2000s, after the first electoral win of the Justice and Development Party (AKP).

Keywords: democracy, Islam, Mustafa Kemal Atatürk, Recep Tayyip Erdoğan, Turkey

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Authors: Ikram Slamani, Hicheme Ferdjani

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This study focuses on analyzing a Griffith crack situated at the center of an infinite strip. The problem is reformulated as a hyper-singular integral equation and solved numerically using second-order Chebyshev polynomials. The primary objective is to calculate the stress intensity factor in mode 1, denoted as K1. The obtained results reveal the influence of the strip width and crack length on the stress intensity factor, assuming stress-free edges. Additionally, a comparison is made with relevant literature to validate the findings.

Keywords: center crack, Chebyshev polynomial, hyper singular integral equation, Griffith, infinite strip, stress intensity factor

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Authors: Kausar Ali

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There are several ground treatment techniques which may meet the twin objectives of increasing the bearing capacity with simultaneous reduction of settlements, but the use of stone columns is one of the most suited techniques for flexible structures such as embankments, oil storage tanks etc. that can tolerate some settlement and used worldwide. However, when the stone columns in very soft soils are loaded; stone columns undergo excessive settlement due to low lateral confinement provided by the soft soil, leading to the failure of the structure. The poor performance of stone columns under these conditions can be improved by encasing the columns with a suitable geosynthetic. In this study, the effect of reinforcement on bearing capacity of composite soil has been investigated by conducting laboratory model tests on floating and end bearing long stone columns with l/d ratio of 12. The columns were reinforced by providing geosynthetic encasement over varying column length (upper 25%, 50%, 75%, and 100% column length). In this study, a group of columns has been used instead of single column, because in the field, columns used for the purpose always remain in groups. The tests indicate that the encasement over the full column length gives higher failure stress as compared to the encasement over the partial column length for both floating and end bearing long columns. The performance of end-bearing columns was found much better than the floating columns.

Keywords: geosynthetic, ground improvement, soft clay, stone column

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Authors: Arefeh Arabaninezhad, Ali Fakher

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Since the deterministic analysis methods fail to take system uncertainties into account, probabilistic and non-probabilistic methods are suggested. Geotechnical analyses are used to determine the stress and deformation caused by construction; accordingly, many input variables which depend on ground behavior are required for geotechnical analyses. The Random Set approach is an applicable reliability analysis method when comprehensive sources of information are not available. Using Random Set method, with relatively small number of simulations compared to fully probabilistic methods, smooth extremes on system responses are obtained. Therefore random set approach has been proposed for reliability analysis in geotechnical problems. In the present study, the application of random set method in reliability analysis of deep excavations is investigated through three deep excavation projects which were monitored during the excavating process. A finite element code is utilized for numerical modeling. Two expected ranges, from different sources of information, are established for each input variable, and a specific probability assignment is defined for each range. To determine the most influential input variables and subsequently reducing the number of required finite element calculations, sensitivity analysis is carried out. Input data for finite element model are obtained by combining the upper and lower bounds of the input variables. The relevant probability share of each finite element calculation is determined considering the probability assigned to input variables present in these combinations. Horizontal displacement of the top point of excavation is considered as the main response of the system. The result of reliability analysis for each intended deep excavation is presented by constructing the Belief and Plausibility distribution function (i.e. lower and upper bounds) of system response obtained from deterministic finite element calculations. To evaluate the quality of input variables as well as applied reliability analysis method, the range of displacements extracted from models has been compared to the in situ measurements and good agreement is observed. The comparison also showed that Random Set Finite Element Method applies to estimate the horizontal displacement of the top point of deep excavation. Finally, the probability of failure or unsatisfactory performance of the system is evaluated by comparing the threshold displacement with reliability analysis results.

Keywords: deep excavation, random set finite element method, reliability analysis, uncertainty

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