Search results for: high tunnel

Authors: Sachin Paul James, Selvasundaram Rajagopal, Muraleedharan Nair, Babu Azariah

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The shot hole borer (SHB), Euwallacea fornicatus (= Xyleborus fornicatus) (Scolytidae: Coleoptera) is one of the major pests of tea in southern India and Sri Lanka. The partially dried cut stem of a jungle plant, Montanoa bipinnatifida (C.Koch) (Compositae: Asteraceae) reported to attract shot hole borer beetles in the field. Collection, isolation, identification and quantification of the emitted volatiles from the partially dried cut stems of M. bipinnatifida using dynamic head space and GC-MS revealed the presence of seven compounds viz. α- pinene, β- phellandrene, β - pinene, D- limonene, trans-caryophyllene, iso- caryophyllene and germacrene– D. Behavioural bioassays using electroantennogram (EAG) and wind tunnel proved that, among these identified compounds only α - pinene, trans-caryophyllene, β – phellandrene and germacrene-D evoked significant behavioral response and maximum response was obtained to a specific blend of these four compounds @ 10:1:0.1:3. Field trapping experiments of this blend conducted in the SHB infested field using multiple funnel traps further proved the efficiency of the blend with a mean trap catch of 176.7 ± 13.1 beetles. Mass trapping studies in the field helped to develop a kairomone trap for the management of SHB in the tea fields of southern India.

Keywords: electroantennogram, kairomone trap, Montanoa bipinnatifida, tea shot hole borer

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Authors: Hyunjung Lim, Jeonghun Nam, Hyuk Choi

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High-throughput separation is an essential technique for cancer research and diagnosis. Here, we propose a viscoelastic microfluidic device for sheathless, high-throughput isolation of circulating tumor cells (CTCs) from white blood cells. Here, we demonstrate a viscoelastic method for separation and concentration of CTCs using closed-loop microfluidics. Our device is a rectangular straight channel with a low aspect ratio. Also, to achieve high-efficiency, high-throughput processing, we used a polymer solution with low viscosity. At the inlet, CTCs and white blood cells (WBCs) were randomly injected into the microchannel. Due to the viscoelasticity-induced lateral migration to the equilibrium positions, large CTCs could be collected from the side outlet while small WBCs were removed at the center outlet. By recirculating the collected CTCs from the side outlet back to the sample reservoir, continuous separation and concentration of CTCs could be achieved with high separation efficiency (~ 99%). We believe that our device has the potential to be applied in resource-limited clinical settings.

Keywords: circulating tumor cell, closed-loop microfluidics, concentration, separation, viscoelastic fluid

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Authors: Fahad Al Shidi, Reginald Victor

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This study was conducted in Northern Oman to assess the physical and chemical characteristics of 40 thermal springs distributed in Al Hajar Mountains in northern Oman. Physical measurements of water samples were carried out in two main seasons in Oman (winter and summer 2019). Studied springs were classified into three groups based on water temperature, four groups based on water pH values and two groups based on conductivity. Ten thermal alkaline springs that originated in Ophiolite (Samail Napp) were dominated by high pH (> 11), elevated concentration of Cl- and Na+ ions, relatively low temperature and discharge ratio. Other springs in the Hajar Super Group massif recorded high concentrations of Ca²+ and SO^2-₄ ions controlled by rock dominance, geochemistry processes, and mineralization. There was only one spring which has brackish water with very high conductivity (5500 µs/cm) and Total Dissolved Solids and it is not suitable for irrigation purposes because of the high abundance of Na+, Cl−, and Ca²+ ions.

Keywords: alkaline springs, geothermal, HSG, ophiolite

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Authors: Mohammed Benlemlih

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Using a sample of 22,839 US firm-year observations over the 1991-2012 period, we find that high CSR firms pay more dividends than low CSR firms. The analysis of individual components of CSR provides strong support for this main finding: five of the six individual dimensions are also associated with high dividend payout. When analyzing the stability of dividend payout, our results show that socially irresponsible firms adjust dividends more rapidly than socially responsible firms do: dividend payout is more stable in high CSR firms. Additional results suggest that firms involved in two controversial activities -the military and alcohol - are associated with low dividend payouts. These findings are robust to alternative assumptions and model specifications, alternative measures of dividend, additional control, and several approaches to address endogeneity. Overall, our results are consistent with the expectation that high CSR firms may use dividend policy to manage the agency problems related to overinvestment in CSR.

Keywords: corporate social responsibility, dividend policy, Lintner model, agency theory, signaling theory, dividend stability

Procedia PDF Downloads 249

Authors: Esmail Sadipour

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The use of social networks is increasing day by day in all societies. The purpose of this research was to know the relationship between the use of social networks (Instagram, WhatsApp, and Telegram) with executive functions and academic performance in first-year female high school students. This research was applied in terms of purpose, quantitative in terms of data type, and correlational in terms of technique. The population of this research consisted of all female high school students in the first year of district 2 of Tehran. Using Green's formula, the sample size of 150 people was determined and selected by cluster random method. In this way, from all 17 high schools in district 2 of Tehran, 5 high schools were selected by a simple random method and then one class was selected from each high school, and a total of 155 students were selected. To measure the use of social networks, a researcher-made questionnaire was used, the Barclay test (2012) was used for executive functions, and last semester's GPA was used for academic performance. Pearson's correlation coefficient and multivariate regression were used to analyze the data. The results showed that there is a negative relationship between the amount of use of social networks and self-control, self-motivation and time self-management. In other words, the more the use of social networks, the fewer executive functions of students, self-control, self-motivation, and self-management of their time. Also, with the increase in the use of social networks, the academic performance of students has decreased.

Keywords: social networks, executive function, academic performance, working memory

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Authors: Veronika Přivřelová

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Well-designed composite steel and concrete structures highlight the good material properties and lower the deficiencies of steel and concrete, in particular they make use of high tensile strength of steel and high stiffness of concrete. The most common composite steel and concrete structure is a simply supported beam, which concrete slab transferring the slab load to a beam is connected to the steel cross-section. The aim of this paper is to find the most adequate numerical model of a simply supported composite beam with the cross-sectional and material parameters based on the results of a processed parametric study and numerical analysis. The paper also evaluates the suitability of using compact concrete with the lightweight aggregates for composite steel and concrete beams. The most adequate numerical model will be used in the resent future to compare the results of laboratory tests.

Keywords: composite beams, high-performance concrete, high-strength steel, lightweight concrete slab, modeling

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Authors: Mohamed Adel Abdallah

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A high voltage magnetic pulse is designed by applying an electrical pulse to the coil. Capacitor banks are developed to generate a pulse current. Switching circuit consisting of DPDT switches, thyristor, and triggering circuit is built and tested. The coil current is measured using a Hall-effect current sensor. The magnetic pulse created is measured and tabulated in the graph. Simulation using FEMM is done to compare the results obtained between experiment and simulation. This technology can be applied to area such as medical equipment, measuring instrument, and military equipment.

Keywords: high voltage, magnetic pulse, capacitor discharge, coil

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Authors: Du T. Tran, Anh M. N. Nguyen

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Writing skill is one of the productive abilities and plays a vital role in encouraging communication. Although certain hurdles limit students from enhancing their writing skills, the introduction and widespread use of internet technology impact their education significantly. In this context, the research aims to investigate the effects of electronic portfolios (e-portfolios) on English as a foreign language (EFL) high school students’ writing ability, learners’ and instructors’ attitudes towards the use of e-portfolios in writing classes at high schools in Binh Duong province. The sample includes 15 teachers and 300 twelfth graders at 03 high schools in Binh Duong province. Facebook was chosen as an e-portfolio platform where the students created and developed their personal e-portfolios. The data were collected both quantitatively and qualitatively through mixed methods using the tools of a pre-test, a post-test (for students), questionnaires (for both teachers and students), and a semi-structured interview (for teachers in charge of the course). The survey results show that e-portfolios considerably impact EFL high school students writing abilities. The research findings also reveal challenges and technological drawbacks. For the optimal use of e-portfolios in writing courses in particular and for other language courses in general, recommendations are made for school managers, instructors, and learners to optimize the effects and for further research to shed more light on the topic

Keywords: attitudes, electronic portfolios, English writing ability, Vietnamese high school students

Procedia PDF Downloads 67

Authors: Makan Cheraghpour, Seyed Ahmad Hosseini, Damoon Ashtary-Larky, Saeed Shirali, Matin Ghanavati, Meysam Alipour

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Background: In addition to reducing body weight, the low-calorie diets can reduce the lean body mass. It is hypothesized that in addition to reducing the body weight, the low-calorie diets can maintain the lean body mass. So, the current study aimed at evaluating the effects of high-protein diet with calorie restriction on body composition in overweight and obese individuals. Methods: 36 obese and overweight subjects were divided randomly into two groups. The first group received a normal-protein, low-energy diet (RDA), and the second group received a high-protein, low-energy diet (2×RDA). The anthropometric indices including height, weight, body mass index, body fat mass, fat free mass, and body fat percentage were evaluated before and after the study. Results: A significant reduction was observed in anthropometric indices in both groups (high-protein, low-energy diets and normal-protein, low-energy diets). In addition, more reduction in fat free mass was observed in the normal-protein, low-energy diet group compared to the high -protein, low-energy diet group. In other the anthropometric indices, significant differences were not observed between the two groups. Conclusion: Independently of the type of diet, low-calorie diet can improve the anthropometric indices, but during a weight loss, high-protein diet can help the fat free mass to be maintained.

Keywords: diet, high-protein, body mass index, body fat percentage

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Authors: Kai-Chee Loh, Jingxin Zhang, Yen-Wah Tong

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Hydrolysis and acidogenesis are the rate-controlling steps in an anaerobic digestion (AD) process. Considering that the optimum conditions for each stage can be diverse diverse, the development of a multi-stage AD system is likely to the AD efficiency through individual optimization. In this research, we developed a highly integrate three-stage anaerobic digester (HM3) to combine the advantages of dry AD and wet AD for anaerobic co-digestion of food waste and horse manure. The digester design comprised mainly of three chambers - high-solids hydrolysis, high-solids acidogenesis and wet methanogensis. Through comparing the treatment performance with other two control digesters, HM3 presented 11.2 ~22.7% higher methane yield. The improved methane yield was mainly attributed to the functionalized partitioning in the integrated digester, which significantly accelerated the solubilization of solid organic matters and the formation of organic acids, as well as ammonia in the high-solids hydrolytic and acidogenic stage respectively. Additionally, HM3 also showed the highest volatile solids reduction rate among the three digesters. Real-time PCR and pyrosequencing analysis indicated that the abundance and biodiversity of microorganisms including bacteria and archaea in HM3 was much higher than that in the control reactors.

Keywords: anaerobic digestion, high-solids, food waste and horse manure, microbial community

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Authors: Robert Jacobsen

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Flood inundation maps (FIMs) are an essential tool in communicating flood threat scenarios to the public as well as in floodplain governance. With an increasing demand for online raster FIMs, the FIM State-of-the-Practice (SOP) is rapidly advancing to meet the dual requirements for high-resolution and high-accuracy—or High-Definition. Importantly, today’s technology also enables the resolution of problems of local—neighborhood-scale—bias errors that often occur in FIMs, even with the use of SOP two-dimensional flood modeling. To facilitate the development of HD-FIMs, a new GIS method--Raster Adjustment with Scenario Profiles, RASPTM—is described for adjusting kernel raster FIMs to match refined scenario profiles. With RASPTM, flood professionals can prepare HD-FIMs for a wide range of scenarios with available kernel rasters, including kernel rasters prepared from vector FIMs. The paper provides detailed procedures for RASPTM, along with an example of applying RASPTM to prepare an HD-FIM for the August 2016 Flood in Louisiana using both an SOP kernel raster and a kernel raster derived from an older vector-based flood insurance rate map. The accuracy of the HD-FIMs achieved with the application of RASPTM to the two kernel rasters is evaluated.

Keywords: hydrology, mapping, high-definition, inundation

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Authors: Ali H. Mahfouz, Hossam E. M. Sallam, Abdulwali Wazir, Hamod H. Kharezi

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The soil profile at site of the bridge project includes soft fine grained soil layer located between 5.0 m to 11.0 m in depth, it has high water content, low SPT no., and low bearing capacity. The clay layer induces high settlement due to surcharge application of earth embankment at ramp T1, ramp T2, and ramp T3 especially at heights from 9m right 3m. Calculated settlement for embankment heights less than 3m may be accepted regarding Saudi Code for soil and foundation. The soil and groundwater at the project site comprise high contents of sulfates and chlorides of high aggressively on concrete and steel bars, respectively. Regarding results of the study, it has been recommended to use stone column piles or new technology named PCC piles as soil improvement to improve the bearing capacity of the weak layer. The new technology is cast in-situ thin wall concrete pipe piles (PCC piles), it has economically advantageous and high workability. The technology can save time of implementation and cost of application is almost 30% of other types of piles.

Keywords: soft foundation soil, bearing capacity, bridge ramps, soil improvement, geogrid, PCC piles

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Authors: Shannon Hearney, Jeffrey Hoch

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While all cancers are costly to treat, pancreatic cancer is a notoriously costly and deadly form of cancer. Across the world there are a variety of treatment centers ranging from small clinics to large, high-volume hospitals as well as differing structures of payment and access. It has been noted that centers that treat a high volume of pancreatic cancer patients have higher quality of care, it is unclear if that care is cost-effective. In the US there is no clear consensus on the cost-effectiveness of high-volume centers for the surgical care of pancreatic cancer. Other European countries, like Finland and Italy have shown that high-volume centers have lower mortality rates and can have lower costs, there however, is still a gap in knowledge about these centers cost-effectiveness globally. This paper seeks to review the current literature in Europe and the US to gain a better understanding of the state of high-volume pancreatic surgical centers cost-effectiveness while considering the contextual differences in health system structure. A review of major reference databases such as Medline, Embase and PubMed will be conducted for cost-effectiveness studies on the surgical treatment of pancreatic cancer at high-volume centers. Possible MeSH terms to be included, but not limited to, are: “pancreatic cancer”, “cost analysis”, “cost-effectiveness”, “economic evaluation”, “pancreatic neoplasms”, “surgical”, “Europe” “socialized medicine”, “privatized medicine”, “for-profit”, and “high-volume”. Studies must also have been available in the English language. This review will encompass European scientific literature, as well as those in the US. Based on our preliminary findings, we anticipate high-volume hospitals to provide better care at greater costs. We anticipate that high-volume hospitals may be cost-effective in different contexts depending on the national structure of a healthcare system. Countries with more centralized and socialized healthcare may yield results that are more cost-effective. High-volume centers may differ in their cost-effectiveness of the surgical care of pancreatic cancer internationally especially when comparing those in the United States to others throughout Europe.

Keywords: cost-effectiveness analysis, economic evaluation, pancreatic cancer, scientific literature review

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Authors: Hossein Ilanloo, Sedigheh Ahmadi, Kianoosh Zahrakar

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The present study aims at investigating the effectiveness of group counseling of mindfulness-based cognitive therapy on cognitive emotion regulation in high school students. The research design was quasi-experimental and pre-test-post-test type and a two-month follow-up with a control group. The statistical population of the study consisted of all-male high school students in Takestan city in the Academic Year 2020-2021. The sample comprised 30 high school male students selected through the convenience sampling method and randomly assigned to experimental (n=15) and control (n=15) groups. The experimental group then received ten sessions of 90-minute group counseling of mindfulness-based cognitive therapy, and the control group did not receive any intervention. In order to collect data, the author used the Cognitive Emotion Regulation Questionnaire (CERQ). The researcher also used multivariate analysis of covariance, repeated measures, LSD post hoc test, and SPSS-26 software for data analysis.

Keywords: mindfulness-based cognitive therapy, cognitive emotion regulation, students, high schools

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Authors: Ravid Yinon

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Introduction: Pelvic trauma causes high mortality, particularly among the elderly population. Pelvic injury ranges from low-energy incidents such as falls to high-energy trauma like motor vehicle accidents. The mortality rate among high-energy trauma patients is higher, as can be expected. The elderly population is more vulnerable to pelvic trauma even at low energy mechanisms due to the fragility and diminished physiological reserve of these patients. The aim of this study is to examine whether there is a higher long-term mortality in pelvic injuries in the elderly from the low-energy mechanism than those injured in high energy. Methods: A retrospective cohort study was conducted in a level 1 trauma center with injured patients aged 65 years and over with pelvic trauma. The patients were divided into two groups of low and high-energy mechanisms of injury. Multivariate analysis was conducted to characterize the differences between the groups. Results: There were 585 consecutive injured patients over the age of 65 with a documented pelvic injury who were treated at the primary trauma center between 2008-2020. The injured in the high energy group were younger (mean HE- 75.18, LE-80.73), with fewer comorbidities (mean 0.78 comorbidities at HE and 1.28 at LE), more men (52.6% at HE and 27.4% at LE), were consumed more treatments facilities such as angioembolization, ICU admission, emergency surgeries and blood products transfusion and higher mortality rate at admission (HE- 19/133, 14.28%, LE- 10/452, 2.21%) compared to the low energy group. However, in a long-term follow-up of one year after the injury, mortality in the low-energy group was significantly higher (HE- 14/114, 12.28%, LE- 155/442, 35.06%). Discussion: Although it can be expected that in the mechanism of high energy, the mortality rate in the long term would be higher, it was found that mortality at the low energy patient was higher. Apparently, low-energy pelvic injury in geriatric patients is a measure of frailty in these patients, causes injury to more frail and morbid patients, and is a predictor of mortality in this population in the long term. Conclusion: The long-term follow-up of injured elderly with pelvic trauma should be more intense, and the healthcare provider should put more emphasis on the rehabilitation of these special patient populations in an attempt to prevent long-term mortality.

Keywords: pelvic trauma, elderly trauma, high energy trauma, low energy trauma

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Authors: Hyo-In Koh, Anders Nordborg, Alex Sievi, Chun-Kwon Park

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The noise source for the interior room of the high speed train is constituted by the rolling contact between the wheel and the rail, aerodynamic noise and structure-borne sound generated through the vibrations of bogie, connection points to the carbody. Air-borne sound is radiated through the panels and structures into the interior room of the trains. The high-speed lines are constructed with slab track systems and many tunnels. The interior noise level and the frequency characteristics vary according to types of the track structure and the infrastructure. In this paper the main sound sources and the transfer paths are studied to find out the contribution characteristics of the sources to the interior noise of a high-speed rail vehicle. For the identification of the acoustic power of each parts of the rolling noise sources a calculation model of wheel/rail noise is developed and used. For the analysis of the transmission of the sources to the interior noise noise and vibration are measured during the operation of the vehicle. According to operation speeds, the mainly contributed sources and the paths could be analyzed. Results of the calculations on the source generation and the results of the measurement with a high-speed train are shown and discussed.

Keywords: rail vehicle, high-speed, interior noise, noise source

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Authors: Silvia Arrate, Waldo Salud, Eloy París

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The wear of cutting tools is one of the most decisive elements when planning tunneling works, programming the maintenance stops and saving the optimum stock of spare parts during the evolution of the excavation. Being able to predict the behavior of cutting tools can give a very competitive advantage in terms of costs and excavation performance, optimized to the needs of the TBM itself. The incredible evolution of data science in recent years gives the option to implement it at the time of analyzing the key and most critical parameters related to machinery with the purpose of knowing how the cutting head is performing in front of the excavated ground. Taking this as a case study, Metro Line 3 of Guadalajara in Mexico will develop the feasibility of using Specific Energy versus data science applied over parameters of Torque, Penetration, and Contact Force, among others, to predict the behavior and status of cutting tools. The results obtained through both techniques are analyzed and verified in the function of the wear and the field situations observed in the excavation in order to determine its effectiveness regarding its predictive capacity. In conclusion, the possibilities and improvements offered by the application of digital tools and the programming of calculation algorithms for the analysis of wear of cutting head elements compared to purely empirical methods allow early detection of possible damage to cutting tools, which is reflected in optimization of excavation performance and a significant improvement in costs and deadlines.

Keywords: cutting tools, data science, prediction, TBM, wear

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Authors: Dong Zhang, Kang Hai Tan, Aravind Dasari

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Increasing concern on environmental sustainability and waste management has driven the construction and building sector towards renewable materials. In this work, we have explored the usage of natural fibers as an alternative to synthetic fibers like polypropylene (PP) in ultra-high performance concrete (UHPC). PP fibers are incorporated into concrete to resist explosive thermal spalling of UHPC during a fire exposure scenario. Experimental studies on the effect of natural fiber on the mechanical properties and spalling resistance of UHCP were conducted. The residual mechanical properties of UHPC with natural fibers were tested after heating to different temperatures. Spalling behavior of UHPC with natural fibers is also assessed by heating the samples according to ISO 834 fire curve. A range of analytical, physical and microscopic characterization techniques was also used on the concrete samples before and after being subjected to elevated temperature to investigate the phase and microstructural change of the sample. The findings show that natural fibers are able to improve fire resistance of UHPC. Adding natural fibers can prevent UHPC from spalling at high temperature. This study provides an alternative, which is at low cost and environmentally friendly, to prevent spalling of UHPC.

Keywords: high temperature, natural fiber, spalling, ultra-high performance concrete

Procedia PDF Downloads 158

Authors: Kyu Bum Han, Eunjin Jeon, Kimberly Watts, Brenda Payan Medina

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Gen3 Concentrating Solar Power (CSP) high-temperature thermal systems have the potential to lower the cost of a CSP system. When compared to the other systems (chloride salt blends and supercritical fluids), the particle transport system can avoid many of the issues associated with high fluid temperature systems at high temperature because of its ability to operate at ambient pressure with limited corrosion or thermal stability risk. Furthermore, identifying and demonstrating low-cost particles that have excellent optical properties and durability can significantly reduce the levelized cost of electricity (LCOE) of particle receivers. The currently available thermal transfer particle in the study and market is oxidized at about 700oC, which reduces its durability, generates particle loss by high friction loads, and causes the color change. To meet the CSP SunShot goal, the durability of particles must be improved by identifying particles that are less abrasive to other structural materials. Furthermore, the particles must be economically affordable and the solar absorptance of the particles must be increased while minimizing thermal emittance. We are studying a novel thermal transfer particle, which has low cost, high durability, and high solar absorptance at high temperatures. The particle minimizes thermal emittance and will be less abrasive to other structural materials. Additionally, the particle demonstrates reusability, which significantly lowers the LCOE. This study will contribute to two principal disciplines of energy science: materials synthesis and manufacturing. Developing this particle for thermal transfer will have a positive impact on the ceramic study and industry as well as the society.

Keywords: concentrating solar power, thermal energy storage, particle, reusability, economics

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Authors: Kadeejah Alsolami, Zainab Alrefay, Husaam Awad

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Obesity and vitamin D deficiency have both been related to cardiovascular disease. The present work aimed to investigate the possible protective effect of vitamin D on cardiac apoptosis in a rat model of dietary-induced obesity. Methods: 30 male Wistar rats included in this study. They were allocated into 4 groups: Control (n=5), animal were fed standard diet for 3 months: Control + vitamin D (VD) (n=5),animals were fed a standard diet with 400IU VD/kg for 3 months: hypercaloric diets group (n=10), animals were fed a high fat diet for 3 months: hypercaloric diet with VD group (n=10), animals were fed a high fat diet with 400IU VD/kg for 3 months. At the beginning of the experiment, the weight and length were measured to assess body mass index (BMI) and repeated every 45 days. Food intake and body weight were monitored throughout the study period. Then rats were sacrificed and heart tissues collected for Quantitative Real-time polymerase chain reaction (qRT-PCR). qRT-PCR used to detect different genetic markers of apoptosis (anti-apoptotic gene (BCL2), a pro-apoptotic gene(BAX), pro-apoptotic genes (FAS, FAS-L), tumour necrosis factor (TNF), mitogen-activated protein kinases (MAPK). Results: FAS and FAS-L gene expression were significantly upregulated in rats fed with high fat diet. And FAS-L gene expression was significantly upregulated in all groups on comparison with control. Whereas Bax gene expression was significantly downregulated in rats fed with high-fat diet supplied with vitamin D. TNF was significantly upregulated in rats fed with high-fat diet treated with vitamin D. MAPK was significantly upregulated in rats fed with high fat diet group, and in rats fed with high-fat diet supplied with vitamin D. Conclusion: The cardiac apoptotic pathways were more activated in rats fed with high-fat than lean rats. And vitamin D protect the heart from the cardiac mitochondrial-dependent apoptotic pathway.

Keywords: apoptosis, heart, obesity, Vitamin D

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Authors: Farid Adisaputra Gumilang

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Kucing Liar Underground Mine is a future mine of PT Freeport Indonesia PTFI that is currently being developed. In the development process, problems were found when blasting the tunnels; there were overbreak, and void occur caused by geological contact or poor rock conditions. Geotechnical engineers must evaluate not only the remnant capacity of ground support systems but also investigate the depth of rock mass yield within pillars. To prevent the potential hazard caused by void zones, geotechnical engineers must ensure the planned drift is mined in the best location where people can work safely. GPR, or Ground penetrating radar, is a geophysical method that can image the subsurface. This non-destructive method uses electromagnetic radiation and detects the reflected signals from subsurface structures. The GPR survey measurements are conducted 48 meters along the drift that has a poor ground condition with 150MHz antenna with several angles (roof, wall, and floor). Concern grounds are determined by the continuity of reflector/low reflector in the radargram section. Concern grounds are determined by the continuity of reflector/low reflector in the radargram section. In this paper, processing data using instantaneous amplitude to identify the void zone. In order to have a good interpretation and result, it combines with the geological information and borehole camera data, so the calibrated GPR data allows the geotechnical engineer to determine the safe location to change the drift location.

Keywords: underground mine, ground penetrating radar, reflectivity, borehole camera

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Authors: Jose Daniel Hoyos Giraldo, Jesus Hernan Jimenez Giraldo, Juan Pablo Alvarado Perilla

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Range and endurance are the main limitations of electric aircraft due to the nature of its source of power. The improvement of efficiency on this kind of systems is extremely meaningful to encourage the aircraft operation with less environmental impact. The propeller efficiency highly affects the overall efficiency of the propulsion system; hence its optimization can have an outstanding effect on the aircraft performance. An optimization method is applied to an aircraft propeller in order to maximize its range and endurance by estimating the best combination of geometrical parameters such as diameter and airfoil, chord and pitch distribution for a specific aircraft design at a certain cruise speed, then the rotational speed at which the propeller operates at minimum current consumption is estimated. The optimization is based on the Blade Element Momentum (BEM) method, additionally corrected to account for tip and hub losses, Mach number and rotational effects; furthermore an airfoil lift and drag coefficients approximation is implemented from Computational Fluid Dynamics (CFD) simulations supported by preliminary studies of grid independence and suitability of different turbulence models, to feed the BEM method, with the aim of achieve more reliable results. Additionally, Vortex Theory is employed to find the optimum pitch and chord distribution to achieve a minimum induced loss propeller design. Moreover, the optimization takes into account the well-known brushless motor model, thrust constraints for take-off runway limitations, maximum allowable propeller diameter due to aircraft height and maximum motor power. The BEM-CFD method is validated by comparing its predictions for a known APC propeller with both available experimental tests and APC reported performance curves which are based on Vortex Theory fed with the NASA Transonic Airfoil code, showing a adequate fitting with experimental data even more than reported APC data. Optimal propeller predictions are validated by wind tunnel tests, CFD propeller simulations and a study of how the propeller will perform if it replaces the one of on known aircraft. Some tendency charts relating a wide range of parameters such as diameter, voltage, pitch, rotational speed, current, propeller and electric efficiencies are obtained and discussed. The implementation of CFD tools shows an improvement in the accuracy of BEM predictions. Results also showed how a propeller has higher efficiency peaks when it operates at high rotational speed due to the higher Reynolds at which airfoils present lower drag. On the other hand, the behavior of the current consumption related to the propulsive efficiency shows counterintuitive results, the best range and endurance is not necessary achieved in an efficiency peak.

Keywords: BEM, blade design, CFD, electric aircraft, endurance, optimization, range

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Authors: Amira Zouaoui, Hamed Belloumi, Ferid Kourda

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This paper presents the analysis and design of a DC–AC resonant converter applied to induction heating. The proposed topology based on the series-parallel half-bridge resonant inverter is described. It can operate with Zero-Voltage Switching (ZVS). At the resonant frequency, the secondary current is amplified over the heating coil with small switching angle, which keeps the reactive power low and permits heating with small current through the resonant inductor and the transformer. The operation and control principle of the proposed high frequency inverter is described and verified through simulated and experimental results.

Keywords: induction heating, inverter, high frequency, resonant

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Authors: Ping Li, Bing Feng, Junpu Zhao, Xudong Xie, Dangpeng Xu, Kuixing Zheng, Qihua Zhu, Xiaofeng Wei

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In laser driven inertial confinement fusion (ICF), the control of the temporal shape of the laser pulse is a key point to ensure an optimal interaction of laser-target. One of the main difficulties in controlling the temporal shape is the foot part control accuracy of high contrast pulse. Based on the analysis of pulse perturbation in the process of amplification and frequency conversion in high power lasers, an approach of beam spatio-temporal multiplexing is proposed to improve the control precision of high contrast pulse. In the approach, the foot and peak part of high contrast pulse are controlled independently, which propagate separately in the near field, and combine together in the far field to form the required pulse shape. For high contrast pulse, the beam area ratio of the two parts is optimized, and then beam fluence and intensity of the foot part are increased, which brings great convenience to the control of pulse. Meanwhile, the near field distribution of the two parts is also carefully designed to make sure their F-numbers are the same, which is another important parameter for laser-target interaction. The integrated calculation results show that for a pulse with a contrast of up to 500, the deviation of foot part can be improved from 20% to 5% by using beam spatio-temporal multiplexing approach with beam area ratio of 1/20, which is almost the same as that of peak part. The research results are expected to bring a breakthrough in power balance of high power laser facility.

Keywords: inertial confinement fusion, laser pulse control, beam spatio-temporal multiplexing, power balance

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Authors: Tlotlollo Sidwell Hlalele, Shengzhi Du

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High voltage transmission is the most pivotal process in the electrical power industry. It requires a robust infrastructure that can last for decades without causing impairment in human life. Due to the so-called global warming, power transmission system has started to experience some challenges which could presumably escalate more in future. These challenges are earthquake resistance, transmission power losses, and high electromagnetic field. In this paper, research efforts aim to address these challenges are discussed. We focus in particular on the research in regenerative electric energy such as: wind, hydropower, biomass and sea-waves based on the energy storage and transmission possibility. We conclude by drawing attention to specific areas that we believe need more research.

Keywords: power transmission, regenerative energy, power quality, energy storage

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Authors: George Mahalu

Abstract:

The Chua diode has been configured over time in various ways, using electronic structures like operational amplifiers (AOs) or devices with gas or semiconductors. When discussing the use of semiconductor devices, tunnel diodes (Esaki diodes) are most often considered, and more recently, transistorized configurations such as lambda diodes. The paperwork proposed here uses in the modeling a lambda diode type configuration consisting of two junction field effect transistors (JFET). The original scheme is created in the MULTISIM electronic simulation environment and is analyzed in order to identify the conditions for the appearance of evolutionary unpredictability specific to nonlinear dynamic systems with chaos-induced behavior. The chaotic deterministic oscillator is one autonomous type, a fact that places it in the class of Chua’s type oscillators, the only significant and most important difference being the presence of a nonlinear device like the one mentioned structure above. The chaotic behavior is identified both by means of strange attractor-type trajectories and visible during the simulation and by highlighting the hypersensitivity of the system to small variations of one of the input parameters. The results obtained through simulation and the conclusions drawn are useful in the further research of ways to implement such constructive electronic solutions in theoretical and practical applications related to modern small signal amplification structures, to systems for encoding and decoding messages through various modern ways of communication, as well as new structures that can be imagined both in modern neural networks and in those for the physical implementation of some requirements imposed by current research with the aim of obtaining practically usable solutions in quantum computing and quantum computers.

Keywords: chua, diode, memristor, chaos

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Authors: Gobinda Gopal Khan, Ashutosh K. Singh, Debasish Sarkar

Abstract:

Unique one-dimensional (1D) Ni-NiO and Co-Ni/Co3O4-NiO core/shell nano-heterostructures are fabricated by combining the electrochemical deposition and annealing. The high-performance pseudo-capacitor electrode based on the Ni-NiO and Co-Ni/Co3O4-NiO core/shell nano-heterostructures is designed and demonstrated. The Co-Ni/Co3O4-NiO core/shell nano-heterostructures exhibit high specific capacitance (2013 Fg-1 at 2.5 Ag-1), high energy and power density (23 Wh kg-1 and 5.5 kW kg-1, at the discharge current density of 20.8 A g-1.), good capacitance retention, and long cyclicality. The remarkable electrochemical property of the large surface area nano-heterostructures is demonstrated based on the novel nano-architectural design of the electrode with the coexistence of the two highly redox active materials at the surface supported by highly conducting metal alloy channel at the core for faster charge transport.

Keywords: nano-heterostructures, energy storage, supercapacitors, electrochemical deposition

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Authors: Saifon Chongthub

Abstract:

The purpose of this research is to synthesize adsorbent foam for CO2 adsorption. The polymer was prepared from poly High Internal Phase Emulsion (PolyHIPE) using styrene as monomer and divinylbenzene as comonomer. Its morphology was determined by Scanning Electron Microscopy (SEM). To further increased CO2 adsorption of the prepared polyHIPE, the layer by layer (LbL) technique was applied, which alternated polyelectrolyte injection between layers of Poly(styrenesulfonate) (PSS) and Poly(diallyldimetyl-ammonium chloride)(PDADMAC) as primary layer, and layers of PSS and polyetyleneimine (PEI) as secondary layer.

Keywords: high internal phase emulsion, polyHIPE, surface modification, layer by layer technique, CO2 adsorption

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Authors: Fahad Aljasass, Hamza Abu-Tarboush, Salah Aleid, Siddig Hamad

Abstract:

The effects of different high hydrostatic pressure treatments on the shelf life of camel’s milk were studied. Treatments at 300 to 350 MPa for 5 minutes at 40°C reduced microbial contamination to levels that prolonged the shelf life of refrigerated (3° C) milk up to 28 days. The treatment resulted in a decrease in the proteolytic activity of the milk. The content of proteolytic enzymes in the untreated milk sample was 4.23 µM/ml. This content decreased significantly to 3.61 µM/ml when the sample was treated at 250 MPa. Treatment at 300 MPa decreased the content to 3.90 which was not significantly different from the content of the untreated sample. The content of the sample treated at 350 MPa dropped to 2.98 µM/ml which was significantly lower than the contents of all other treated and untreated samples. High pressure treatment caused a slight but statistically significant increase in the pH of camel’s milk. The pH of the untreated sample was 6.63, which increased significantly to 6.70, in the samples treated at 250 and 350 MPa, but insignificantly in the sample treated at 300 MPa. High pressure treatment resulted in some degree of milk fat oxidation. The thiobarbituric acid (TBA) value of the untreated sample was 0.86 mg malonaldehyde/kg milk. This value remained unchanged in the sample treated at 250 MPa, but then it increased significantly to 1.25 and 1.33 mg/kg in the samples treated at 300 and 350 MPa, respectively. High pressure treatment caused a small increase in the greenness (a* value) of camel’s milk. The value of a* was reduced from -1.17 for the untreated sample to -1.26, -1.21 and -1.30 for the samples treated at 250, 300 and 350 MPa, respectively. Δa* at the 250 MPa treatment was -0.09, which then decreased to -0.04 at the 300 MPa treatment to increase again to -0.13 at the 350 MPa treatment. The yellowness (b* value) of camel’s milk increased significantly as a result of high pressure treatment. The b* value of the untreated sample was 1.40, this value increased to 2.73, 2.31 and 2.18 after treatments at 250, 300 and 350 MPa, respectively. The Δb* value was +1.33 at the treatment 250 MPa, decreased to +0.91 at 300 MPa and further to +0.78 at 350 MPa. The pressure treatment caused slight effect on color, slight decrease in protease activity and a slight increase in the oxidation products of lipids.

Keywords: high hydrostatic pressure, camel’s milk, mesophilic aerobic bacteria, clotting, protease

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Authors: Florge Francis A. Sy

Abstract:

Physicians develop emotional and psychological distress after facing a patient’s death. This can result in stress or burnout. Coping mechanisms in dealing with these deaths may be maladaptive. Determining grief, emotional impact, and coping strategies in physicians is necessary to identify those needing intervention. This can be done by employing validated assessment tools such as the Texas Revised Inventory of Grief (TRIG) scale, Impact of Events Scale (IES), and BriefCOPE tool, respectively. This prospective, observational study was done in a private hospital in Cebu City. Fifty-five internal medicine residents were included and tasked to answer a survey based on their most memorable patient death encounter. The TRIG, IES, and BriefCOPE scores were determined. Participants were divided into severe grief and non-severe grief based on TRIG scores, low-impact, moderate-impact, and high-impact based on IES, and low-use, moderate-use, and high-use based on the BriefCOPE. The differences in the groups’ characteristics were statistically determined, and a p-value of < 0.05 was significant. The participants’ average age was 28.45 years. Most were female and single. Most belonged to the non-severe group based on TRIG, a moderate-impact group based on the IES, and high-use group based on the BriefCOPE. However, 21.8% reported severe grief, 27.3% reported high-impact, and 10.9% had low use of coping strategies. The proportion of residents who encountered CPR prior to the patient’s death was greater in the severe group. Proportions of both high-impact and non-high impact groups were comparable. The proportion of female residents was higher in the high-use group. There were a number of residents who reported severe grief, high emotional impact, and low coping strategies. This highlights the need for interventions such as debriefing after CPR or formal training in residency programs in dealing with emotional burden to counteract maladaptive coping behaviors and prevent negative outcomes.

Keywords: residents, grief, emotional impact, coping, patient death

Procedia PDF Downloads 102