Search results for: power quality evaluation
Commenced in January 2007
Frequency: Monthly
Edition: International
Paper Count: 19848

Search results for: power quality evaluation

4218 Using Wearable Device with Neuron Network to Classify Severity of Sleep Disorder

Authors: Ru-Yin Yang, Chi Wu, Cheng-Yu Tsai, Yin-Tzu Lin, Wen-Te Liu

Abstract:

Background: Sleep breathing disorder (SDB) is a condition demonstrated by recurrent episodes of the airway obstruction leading to intermittent hypoxia and quality fragmentation during sleep time. However, the procedures for SDB severity examination remain complicated and costly. Objective: The objective of this study is to establish a simplified examination method for SDB by the respiratory impendence pattern sensor combining the signal processing and machine learning model. Methodologies: We records heart rate variability by the electrocardiogram and respiratory pattern by impendence. After the polysomnography (PSG) been done with the diagnosis of SDB by the apnea and hypopnea index (AHI), we calculate the episodes with the absence of flow and arousal index (AI) from device record. Subjects were divided into training and testing groups. Neuron network was used to establish a prediction model to classify the severity of the SDB by the AI, episodes, and body profiles. The performance was evaluated by classification in the testing group compared with PSG. Results: In this study, we enrolled 66 subjects (Male/Female: 37/29; Age:49.9±13.2) with the diagnosis of SDB in a sleep center in Taipei city, Taiwan, from 2015 to 2016. The accuracy from the confusion matrix on the test group by NN is 71.94 %. Conclusion: Based on the models, we established a prediction model for SDB by means of the wearable sensor. With more cases incoming and training, this system may be used to rapidly and automatically screen the risk of SDB in the future.

Keywords: sleep breathing disorder, apnea and hypopnea index, body parameters, neuron network

Procedia PDF Downloads 120
4217 The Perceptions of Students in Tourism and Hospitality in Relation to the Pursuit of Higher Degrees: A Case of Walter Sisulu University

Authors: Adelaide Rethabile Motshabi Pitso-Mbili

Abstract:

Higher education institutions (HEIs) are under pressure in producing PhD graduates so that they can position themselves higher in terms of rankings. However, hospitality and tourism higher degree enrolment numbers are very low within South African universities. Furthermore, hospitality and tourism students choose these fields of study because they want to travel, be social, and have fun. Students in higher education are anxious about their future after studies as they are particularly worried about the job conditions in the hospitality and tourism sector, the remuneration, and the status perceptions of many jobs in the sector. Hence, there is a need for a continuous increase in the level of education with the formation of professional aptitudes and personnel quality. In order to understand the reasons for low enrolments, this study aims to explore the perceptions of the final year in tourism and hospitality diploma students towards enrolling for higher degree qualifications after their graduation. This paper utilised a quantitative research method, and data was gathered through questionnaires. In addition, the Linkert scale design was used for questionnaires. The questionnaires were distributed to 137 hospitality and tourism students who are on their exit level at Walter Sisulu University. SPSS was used to analyse data. The findings revealed that students do not wish to continue studying for higher degrees as they believe higher degrees are not important for the industry. Furthermore, families already have financial expectations as they think one qualification is enough. In addition, some students mentioned that they would love to study further, but lack of funding is a problem since NSFAS only funds the first qualification. Thus, it is recommended that students are made aware of the benefits and opportunities available after obtaining higher degrees.

Keywords: hospitality and tourism education, higher degrees, higher education, student’s perceptions, hospitality and tourism sector

Procedia PDF Downloads 92
4216 Experiences of Marital Relationship of Middle-Aged Couples in Hong Kong: Implications for Services Interventions

Authors: Wai M. Shum

Abstract:

There was evidence that the change of marital quality satisfaction was related to the different stages of the family life cycle. Research studies have been largely based on western contexts, which found a curvilinear U-shaped trend in changes of marital satisfaction over the course of a marriage, but little is known about the marital experiences of Hong Kong couples. Through in-depth interviews, this qualitative study explored the marital relationship of middle-aged couples in a satisfying marriage and to identify how couples maintain a satisfying relationship in the local context. Findings from this study suggested twelve themes with some showing consistency with previous literature, such as communication, companionship, trust, and fidelity. The affective aspects of empathetic understanding and perceived empathy were found to have an enormous effect on couples’ bondedness. The high level of differentiation and security served as a basis for unconditional contribution, acceptance, and adjustment to unsolvable issues such that negative emotion would not be escalated. The manifestations of intimacy and commitment in the triangular theory of love were more frequently addressed than passion in striving for marital longevity in the local context. This study challenged the curvilinear trend of marital satisfaction throughout marriage, with couples showing different pathways of marital satisfaction. The study gave insights on martial enrichment, such as facilitating couples to disclose their vulnerabilities, desire for physical intimacy, and passion in the pursuit of enduring marriage instead of an emphasis on skills training on communication and conflict resolution.

Keywords: intimacy, marital relationship, marital satisfaction, middle-aged

Procedia PDF Downloads 92
4215 Modeling and Design of E-mode GaN High Electron Mobility Transistors

Authors: Samson Mil'shtein, Dhawal Asthana, Benjamin Sullivan

Abstract:

The wide energy gap of GaN is the major parameter justifying the design and fabrication of high-power electronic components made of this material. However, the existence of a piezo-electrics in nature sheet charge at the AlGaN/GaN interface complicates the control of carrier injection into the intrinsic channel of GaN HEMTs (High Electron Mobility Transistors). As a result, most of the transistors created as R&D prototypes and all of the designs used for mass production are D-mode devices which introduce challenges in the design of integrated circuits. This research presents the design and modeling of an E-mode GaN HEMT with a very low turn-on voltage. The proposed device includes two critical elements allowing the transistor to achieve zero conductance across the channel when Vg = 0V. This is accomplished through the inclusion of an extremely thin, 2.5nm intrinsic Ga₀.₇₄Al₀.₂₆N spacer layer. The added spacer layer does not create piezoelectric strain but rather elastically follows the variations of the crystal structure of the adjacent GaN channel. The second important factor is the design of a gate metal with a high work function. The use of a metal gate with a work function (Ni in this research) greater than 5.3eV positioned on top of n-type doped (Nd=10¹⁷cm⁻³) Ga₀.₇₄Al₀.₂₆N creates the necessary built-in potential, which controls the injection of electrons into the intrinsic channel as the gate voltage is increased. The 5µm long transistor with a 0.18µm long gate and a channel width of 30µm operate at Vd=10V. At Vg =1V, the device reaches the maximum drain current of 0.6mA, which indicates a high current density. The presented device is operational at frequencies greater than 10GHz and exhibits a stable transconductance over the full range of operational gate voltages.

Keywords: compound semiconductors, device modeling, enhancement mode HEMT, gallium nitride

Procedia PDF Downloads 244
4214 Method for Targeting Small Volume in Rat Brainby Gamma Knife and Dosimetric Control: Towards a Standardization

Authors: J. Constanzo, B. Paquette, G. Charest, L. Masson-Côté, M. Guillot

Abstract:

Targeted and whole-brain irradiation in humans can result in significant side effects causing decreased patient quality of life. To adequately investigate structural and functional alterations after stereotactic radiosurgery, preclinical studies are needed. The first step is to establish a robust standardized method of targeted irradiation on small regions of the rat brain. Eleven euthanized male Fischer rats were imaged in a stereotactic bed, by computed tomographic (CT), to estimate positioning variations regarding to the bregma skull reference point. Using a rat brain atlas and the stereotactic bregma coordinates assessed from CT images, various regions of the brain were delimited and a treatment plan was generated. A dose of 37 Gy at 30% isodose which corresponds to 100 Gy in 100% of the target volume (X = 98.1; Y = 109.1; Z = 100.0) was set by Leksell Gamma Plan using sectors number 4, 5, 7, and 8 of the Gamma Knife unit with the 4-mm diameter collimators. Effects of positioning accuracy of the rat brain on the dose deposition were simulated by Gamma Plan and validated with dosimetric measurements. Our results showed that 90% of the target volume received 110 ± 4.7 Gy and the maximum of deposited dose was 124 ± 0.6 Gy, which corresponds to an excellent relative standard deviation of 0.5%. This dose deposition calculated with the Gamma Plan was validated with the dosimetric films resulting in a dose-profile agreement within 2%, both in X- and Z-axis,. Our results demonstrate the feasibility to standardize the irradiation procedure of a small volume in the rat brain using a Gamma Knife.

Keywords: brain irradiation, dosimetry, gamma knife, small-animal irradiation, stereotactic radiosurgery (SRS)

Procedia PDF Downloads 390
4213 Status of Production, Distribution and Determinants of Biomass Briquette Acceptability in Kampala, Uganda

Authors: David B. Kisakye, Paul Mugabi

Abstract:

Biomass briquettes have been identified as a plausible and close alternative to commonly used energy fuels such as charcoal and firewood, whose prices are escalating due to the dwindling natural resource base. However, briquettes do not seem to be as popular as would be expected. This study assessed the production, distribution, and acceptability of the briquettes in the Kampala district. A total of 60 respondents, 50 of whom were briquette users and 10 briquette producers, were sampled from five divisions of Kampala district to evaluate consumer acceptability, preference for briquette type and shape. Households and institutions were identified to be the major consumers of briquettes, while community-based organizations were the major distributors of briquettes. The Chi-square test of independence showed a significant association between briquette acceptability and briquette attributes of substitutability and low cost (p < 0,05). The Kruskal Wallis test showed that low-income class people preferred non-carbonized briquettes. Gender, marital status, and income level also cause variation in preference for spherical, stick, and honeycomb briquettes (p < 0,05). The major challenges faced by briquette users in Kampala were; production of a lot of ash, frequent crushing, and limited access to briquettes. The producers of briquettes were mainly challenged by regular machine breakdown, raw material scarcity, and poor carbonizing units. It was concluded that briquettes have a market and are generally accepted in Kampala. However, user preferences need to be taken into account by briquette produces, suitable cookstoves should be availed to users, and there is a need for standards to ensure the quality of briquettes.

Keywords: consumer acceptability, biomass residues, briquettes, briquette producers, distribution, fuel, marketability, wood fuel

Procedia PDF Downloads 114
4212 The Evaluation of the Restructuring Process in Nursing Services by Nurses

Authors: Bilgen Özlük, Ülkü Baykal

Abstract:

The study was conducted with the aim of determining the evaluations of nurses directed at the restructuring process carried out in the nursing services of a private hospital, and reveal how they have been affected by this process, in an integrated manner between a prospective approach and methods of quantitative and qualitative research, and as a comparative study, comparing the changes over a period of three years. The sample for the study is comprised of all of the nurses employed at a private hospital, and data has been collected from 17 nurses (a total of 30 interviews) for the qualitative part 377 nurses in 2013 and 429 nurses in 2014 for the quantitative part. As vehicles of data collection, the study used a form directed at identifying the changes in the organisational and management structure of the hospital, a nurses' interview form, a questionnaire identifying the personal and occupational characteristics of the nurses, the "Minnesota Job Satisfaction Scale", the "Organisational Citizenship Behaviour Scale" and the "Organisational Trust Scale". Qualitative data by researchers, quantitative data was analysed using number and percentage tests, a t-test, and ANOVA, progressive analysis Tukey and regression tests. While in the qualitative part of the study the nurses stated in the first year of the restructuring that they were satisfied with their relationship with top level management, the increases in salaries and changes in the working environment such as the increase in the number of staff, in later years, they stated that there had been a fall in their satisfaction levels due to reasons such as nursing services instead of nurse practitioners in a position they are not satisfied that the director, nursing services outside the nursing profession appointment of persons to positions of management and the lack of appropriate training and competence of these persons, increases in the burden of work, insufficient salaries and the lack of a difference in the salaries of senior and more junior staff. On the other hand, in the quantitative part, it was found that there was no difference in the levels of job satisfaction and organisational trust in any of the two years, that as the level of organisational trust increased the level of job satisfaction also increased, and that as the levels of job satisfaction and organisational trust a positive impact on organisational citizenship behaviour also increased.

Keywords: services, nursing management, re-structuring, job satisfaction, organisational citizenship behaviour, organisational trust

Procedia PDF Downloads 342
4211 Generative Adversarial Network Based Fingerprint Anti-Spoofing Limitations

Authors: Yehjune Heo

Abstract:

Fingerprint Anti-Spoofing approaches have been actively developed and applied in real-world applications. One of the main problems for Fingerprint Anti-Spoofing is not robust to unseen samples, especially in real-world scenarios. A possible solution will be to generate artificial, but realistic fingerprint samples and use them for training in order to achieve good generalization. This paper contains experimental and comparative results with currently popular GAN based methods and uses realistic synthesis of fingerprints in training in order to increase the performance. Among various GAN models, the most popular StyleGAN is used for the experiments. The CNN models were first trained with the dataset that did not contain generated fake images and the accuracy along with the mean average error rate were recorded. Then, the fake generated images (fake images of live fingerprints and fake images of spoof fingerprints) were each combined with the original images (real images of live fingerprints and real images of spoof fingerprints), and various CNN models were trained. The best performances for each CNN model, trained with the dataset of generated fake images and each time the accuracy and the mean average error rate, were recorded. We observe that current GAN based approaches need significant improvements for the Anti-Spoofing performance, although the overall quality of the synthesized fingerprints seems to be reasonable. We include the analysis of this performance degradation, especially with a small number of samples. In addition, we suggest several approaches towards improved generalization with a small number of samples, by focusing on what GAN based approaches should learn and should not learn.

Keywords: anti-spoofing, CNN, fingerprint recognition, GAN

Procedia PDF Downloads 171
4210 Using Linear Logistic Regression to Evaluation the Patient and System Delay and Effective Factors in Mortality of Patients with Acute Myocardial Infarction

Authors: Firouz Amani, Adalat Hoseinian, Sajjad Hakimian

Abstract:

Background: The mortality due to Myocardial Infarction (MI) is often occur during the first hours after onset of symptom. So, for taking the necessary treatment and decreasing the mortality rate, timely visited of the hospital could be effective in this regard. The aim of this study was to investigate the impact of effective factors in mortality of MI patients by using Linear Logistic Regression. Materials and Methods: In this case-control study, all patients with Acute MI who referred to the Ardabil city hospital were studied. All of died patients were considered as the case group (n=27) and we select 27 matched patients without Acute MI as a control group. Data collected for all patients in two groups by a same checklist and then analyzed by SPSS version 24 software using statistical methods. We used the linear logistic regression model to determine the effective factors on mortality of MI patients. Results: The mean age of patients in case group was significantly higher than control group (75.1±11.7 vs. 63.1±11.6, p=0.001).The history of non-cardinal diseases in case group with 44.4% significantly higher than control group with 7.4% (p=0.002).The number of performed PCIs in case group with 40.7% significantly lower than control group with 74.1% (P=0.013). The time distance between hospital admission and performed PCI in case group with 110.9 min was significantly upper than control group with 56 min (P=0.001). The mean of delay time from Onset of symptom to hospital admission (patient delay) and the mean of delay time from hospital admissions to receive treatment (system delay) was similar between two groups. By using logistic regression model we revealed that history of non-cardinal diseases (OR=283) and the number of performed PCIs (OR=24.5) had significant impact on mortality of MI patients in compare to other factors. Conclusion: Results of this study showed that of all studied factors, the number of performed PCIs, history of non-cardinal illness and the interval between onset of symptoms and performed PCI have significant relation with morality of MI patients and other factors were not meaningful. So, doing more studies with a large sample and investigated other involved factors such as smoking, weather and etc. is recommended in future.

Keywords: acute MI, mortality, heart failure, arrhythmia

Procedia PDF Downloads 109
4209 Modeling Karachi Dengue Outbreak and Exploration of Climate Structure

Authors: Syed Afrozuddin Ahmed, Junaid Saghir Siddiqi, Sabah Quaiser

Abstract:

Various studies have reported that global warming causes unstable climate and many serious impact to physical environment and public health. The increasing incidence of dengue incidence is now a priority health issue and become a health burden of Pakistan. In this study it has been investigated that spatial pattern of environment causes the emergence or increasing rate of dengue fever incidence that effects the population and its health. The climatic or environmental structure data and the Dengue Fever (DF) data was processed by coding, editing, tabulating, recoding, restructuring in terms of re-tabulating was carried out, and finally applying different statistical methods, techniques, and procedures for the evaluation. Five climatic variables which we have studied are precipitation (P), Maximum temperature (Mx), Minimum temperature (Mn), Humidity (H) and Wind speed (W) collected from 1980-2012. The dengue cases in Karachi from 2010 to 2012 are reported on weekly basis. Principal component analysis is applied to explore the climatic variables and/or the climatic (structure) which may influence in the increase or decrease in the number of dengue fever cases in Karachi. PC1 for all the period is General atmospheric condition. PC2 for dengue period is contrast between precipitation and wind speed. PC3 is the weighted difference between maximum temperature and wind speed. PC4 for dengue period contrast between maximum and wind speed. Negative binomial and Poisson regression model are used to correlate the dengue fever incidence to climatic variable and principal component score. Relative humidity is estimated to positively influence on the chances of dengue occurrence by 1.71% times. Maximum temperature positively influence on the chances dengue occurrence by 19.48% times. Minimum temperature affects positively on the chances of dengue occurrence by 11.51% times. Wind speed is effecting negatively on the weekly occurrence of dengue fever by 7.41% times.

Keywords: principal component analysis, dengue fever, negative binomial regression model, poisson regression model

Procedia PDF Downloads 421
4208 Is Hormone Replacement Therapy Associated with Age-Related Macular Degeneration? A Systematic Review and Meta-Analysis

Authors: Hongxin Zhao, Shibing Yang, Bingming Yi, Yi Ning

Abstract:

Background: A few studies have found evidence that exposure to endogenous or postmenopausal exogenous estrogens may be associated with a lower prevalence of age-related macular degeneration (AMD), but dispute over this association is ongoing due to inconsistent results reported by different studies. Objectives: To conduct a systematic review and meta-analysis to investigate the association between hormone replacement therapy (HRT) use and AMD. Methods: Relevant studies that assessed the association between HRT and AMD were searched through four databases (PubMed, Web of Science, Cochrane Library, EMBASE) and reference lists of retrieved studies. Study selection, data extraction and quality assessment were conducted by three independent reviewers. The fixed-effect meta-analyses were performed to estimate the association between HRT ever-use and AMD by pooling risk ratio (RR) or odds ratio (OR) across studies. Results: The review identified 2 prospective and 7 cross-sectional studies with 93992 female participants that reported an estimate of the association between HRT ever-use and presence of early AMD or late AMD. Meta-analyses showed that there were no statistically significant associations between HRT ever-use and early AMD (pooled RR for cohort studies was 1.04, 95% CI 0.86 - 1.24; pooled OR for cross-sectional studies was 0.91, 95% CI 0.82 - 1.01). The pooled results from cross-sectional studies also showed no statistically significant association between HRT ever-use and late AMD (OR 1.01; 95% CI 0.89 - 1.15). Conclusions: The pooled effects from observational studies published to date indicate that HRT use is associated with neither early nor late AMD. Exposure to HRT may not protect women from developing AMD.

Keywords: hormone replacement therapy, age-related macular degeneration, meta-analysis, systematic review

Procedia PDF Downloads 334
4207 Hypoglycaemic and Hypolipidemic Activity of Cassia occidentalis Linn. Stem Bark Extract in Streptozotocin Induced Diabetes

Authors: Manjusha Choudhary

Abstract:

Objective: Cassia occidentalis Linn. belongs to Family Caesalpiniaceae is a common weed scattered from the foothills of Himalayas to West Bengal, South India, Burma, and Sri Lanka. It is used widely in folklore medicine in India as laxative, expectorant, analgesic, anti-malarial, hepatoprotective, relaxant, anti-inflammatory and antidiabetic. The present study was carried out to investigate the hypoglycaemic and hypolipidemic activities of ethanolic extract of Cassia occidentalis stem bark. Methods: Stem bark extract of Cassia occidentalis (SBCO) was administered orally at 250 and 500 mg/kg doses to normal and streptozotocin (STZ) induced type-2 diabetic mice. Various parameters like fasting blood glucose (FBG) level, serum cholesterol, high density lipoprotein (HDL) cholesterol, triglycerides (TG), total protein, urea, creatinine, serum glutamate oxaloacetate transaminase (SGOT), serum glutamate pyruvate transaminase (SGPT) levels and physical parameters like change in body weight, food intake, water intake were performed for the evaluation of antidiabetic effects. Results: Both the doses of extract caused a marked decrease in FBG levels in STZ induced type 2 diabetic mice. Administration of SBCO led to the decrease in the blood glucose, food intake, water intake, organ weight, SGOT, SGPT levels with significant value and increased the levels of TG, HDL cholesterol, creatinine, cholesterol, total protein with a significant value (p < 0.05-0.01). The decrease in body weight induced by STZ was restored to normal with a significant value (p < 0.01) at both doses. Conclusion: Present study reveals that SBCO possess potent hypoglycaemic and hypolipidemic activities and supports the folklore use of the stem bark of plant as antidiabetic agent.

Keywords: Cassia occidentalis, diabetes, folklore, herbs, hypoglycemia, streptozotocin

Procedia PDF Downloads 381
4206 Study on Shelf Life and Textural Properties of Minimal Processed Mixed Fruits

Authors: Kaavya Rathnakumar

Abstract:

Minimally processed fruits have the attributes of convenience and fresh like quality. In minimally processed products, the cells of the tissue are alive, and the essential nutrients and flavours are retained. Some of the procedures include washing, trimming, sorting, cutting, slicing and shredding. Fruits such as pineapple and guava were taken for the study of textural properties for a period of five days. After the performance of various unit operations 50g cubes of pineapple and guava has been weighed. For determining the textural properties, samples were taken in which set of 12 samples were treated by using 1% citric acid solution and dried for 5 minutes the remaining set of 12 samples were untreated. In set of treated samples 6 were vacuum packed and stored in the refrigerator, and the other sample was normally stored. For untreated samples was done in a similar way. In texture profile analysis the force required for 1cm penetration of 2mm cylindrical needle inside the fruits were recorded for all packages. It was observed that guava the fresh sample had a force of penetration of 3250mm and as the days increased the force decreased to 357.4 mm for vacuum packed refrigerated storage. In the case of pineapple, the force of penetration of the fresh sample was 2325mm which was decreased to 26.3mm on the fourth day and very low at the fifth day for vacuum packed refrigerated storage. But in case of untreated samples, the fruits were spoiled may be because of no pre-treatment and packaging. Comparatively, it was found that vacuum packed refrigerated samples had higher shelf life than normal packed samples in ambient conditions.

Keywords: 1% citric acid solution, normal packed, refrigerated storage, vacuum packed

Procedia PDF Downloads 179
4205 Causes of Deteriorations of Flexible Pavement, Its Condition Rating and Maintenance

Authors: Pooja Kherudkar, Namdeo Hedaoo

Abstract:

There are various causes for asphalt pavement distresses which can develop prematurely or with aging in services. These causes are not limited to aging of bitumen binder but include poor quality materials and construction, inadequate mix design, inadequate pavement structure design considering the traffic and lack of preventive maintenance. There is physical evidence available for each type of pavement distress. Distress in asphalt pavements can be categorized in different distress modes like fracture (cracking and spalling), distortion (permanent deformation and slippage), and disintegration (raveling and potholes). This study shows the importance of severity determination of distresses for the selection of appropriate preventive maintenance treatment. Distress analysis of the deteriorated roads was carried out. Four roads of urban flexible pavements from Pune city was selected as a case study. The roads were surveyed to detect the types, to measure the severity and extent of the distresses. Causes of distresses were investigated. The pavement condition rating values of the roads were calculated. These ranges of ratings were as follows; 1 for poor condition road, 1.1 to 2 for fair condition road and 2.1 to 3 for good condition road. Out of the four roads, two roads were found to be in fair condition and the other two were found in good condition. From the various preventive maintenance treatments like crack seal, fog seal, slurry seal, microsurfacing, surface dressing and thin hot mix/cold mix bituminous overlays, the effective maintenance treatments with respect to the surface condition and severity levels of the existing pavement were recommended.

Keywords: distress analysis, pavement condition rating, preventive maintenance treatments, surface distress measurement

Procedia PDF Downloads 166
4204 Experimental Study of Complete Loss of Coolant Flow (CLOF) Test by System–Integrated Modular Advanced Reactor Integral Test Loop (SMART-ITL) with Passive Residual Heat Removal System (PRHRS)

Authors: Jin Hwa Yang, Hwang Bae, Sung Uk Ryu, Byong Guk Jeon, Sung Jae Yi, Hyun Sik Park

Abstract:

Experimental studies using a large-scale thermal-hydraulic integral test facility, System–integrated Modular Advanced Reactor Integral Test Loop (SMART-ITL), have been carried out to validate the performance of the prototype, SMART. After Fukushima accident, the passive safety systems have been dealt as important designs for retaining of nuclear safety. One of the concerned scenarios for evaluating the passive safety system is a Complete Loss of Coolant Flow (CLOF). The flowrate of coolant in the primary system is maintained by Reactor Coolant Pump (RCP). When the supply of electric power of RCP is shut off, the flowrate of coolant decreases sharply, and the temperature of the coolant increases rapidly. Therefore, the reactor trip signal is activated to prevent the over-heating of the core. In this situation, Passive Residual Heat Removal System (PRHRS) plays a significant role to assure the soundness of the SMART. The PRHRS using a two-phase natural circulation is a passive safety system in the SMART to eliminate the heat of steam generator in the secondary system with heat exchanger submarined in the Emergency Cooling Tank (ECT). As the RCPs continue to coast down, inherent natural circulation in the primary system transfers heat to the secondary system. The transferred heat is removed by PRHRS in the secondary system. In this paper, the progress of the CLOF accident is described with experimental data of transient condition performed by SMART-ITL. Finally, the capability of passive safety system and inherent natural circulation will be evaluated.

Keywords: CLOF, natural circulation, PRHRS, SMART-ITL

Procedia PDF Downloads 421
4203 Agile Implementation of 'PULL' Principles in a Manufacturing Process Chain for Aerospace Composite Parts

Authors: Torsten Mielitz, Dietmar Schulz, York C. Roth

Abstract:

Market forecasts show a significant increase in the demand for aircraft within the next two decades and production rates will be adapted accordingly. Improvements and optimizations in the industrial system are becoming more important to cope with future challenges in manufacturing and assembly. Highest quality standards have to be met for aerospace parts, whereas cost effective production in industrial systems and methodologies are also a key driver. A look at other industries like e.g., automotive shows well established processes to streamline existing manufacturing systems. In this paper, the implementation of 'PULL' principles in an existing manufacturing process chain for a large scale composite part is presented. A nonlinear extrapolation based on 'Little's Law' showed a risk of a significant increase of parts needed in the process chain to meet future demand. A project has been set up to mitigate the risk whereas the methodology has been changed from a traditional milestone approach in the beginning towards an agile way of working in the end in order to facilitate immediate benefits in the shop-floor. Finally, delivery rates could be increased avoiding more semi-finished parts in the process chain (work in progress & inventory) by the successful implementation of the 'PULL' philosophy in the shop-floor between the work stations. Lessons learned during the running project as well as implementation and operations phases are discussed in order to share best practices.

Keywords: aerospace composite part manufacturing, PULL principles, shop-floor implementation, lessons learned

Procedia PDF Downloads 154
4202 Project Design Deliverables Sequence (PDD)

Authors: Nahed Al-Hajeri

Abstract:

There are several reasons which lead to a delay in project completion, out of all, one main reason is the delay in deliverable processing, i.e. submission and review of documents. Most of the project cycles start with a list of deliverables but without a sequence of submission of the same, means without a direction to move, leading to overlapping of activities and more interdependencies. Hence Project Design Deliverables (PDD) is developed as a solution to Organize Transmittals (Documents/Drawings) received from contractors/consultants during different phases of an EPC (Engineering, Procurement, and Construction) projects, which gives proper direction to the stakeholders from the beginning, to reduce inter-discipline dependency, avoid overlapping of activities, provide a list of deliverables, sequence of activities, etc. PDD attempts to provide a list and sequencing of the engineering documents/drawings required during different phases of a Project which will benefit both client and Contractor in performing planned activities through timely submission and review of deliverables. This helps in ensuring improved quality and completion of Project in time. The successful implementation begins with a detailed understanding the specific challenges and requirements of the project. PDD will help to learn about vendor document submissions including general workflow, sequence and monitor the submission and review of the deliverables from the early stages of Project. This will provide an overview for the Submission of deliverables by the concerned during the projects in proper sequence. The goal of PDD is also to hold responsible and accountability of all stakeholders during complete project cycle. We believe that successful implementation of PDD with a detailed list of documents and their sequence will help organizations to achieve the project target.

Keywords: EPC (Engineering, Procurement, and Construction), project design deliverables (PDD), econometrics sciences, management sciences

Procedia PDF Downloads 377
4201 Digital Female Entrepreneurs in South Africa: Drivers and Relationship to Economic Development

Authors: C. van den Berg, C. Pokpas

Abstract:

Popular discourse touts entrepreneurship as a universal solution for underdevelopment, unemployment, and poverty. Moreover, claims are made that women and other disadvantaged groups can achieve material and personal success through digital entrepreneurship. This paper examines the potential of digital technology in entrepreneurial ventures to stimulate economic growth for marginalized groups and communities. Although digital entrepreneurship is hailed as a means to empower under-resourced and socially marginalized people, these opportunities still exist within the confines of existing social and cultural practices. The perspectives of female digital entrepreneurs in developing countries are sorely understudied, particularly concerning an understanding of the complex underlying socio-cultural factors impeding women’s entrepreneurial behaviors. This qualitative study, guided by a feminist phenomenological perspective, focused on the experiences of digital female entrepreneurs in the Western Cape of South Africa. Data were collected via semi-structured interviews and analyzed through the interpretative phenomenological analysis (IPA) approach to determine the relationships between digital entrepreneurship and structural and agential enabling conditions. Findings show that digital entrepreneurship is not a panacea for economic growth in marginalized groups and communities and highlight the importance of addressing socio-cultural gender inequality to enable successful entrepreneurial activity. The paper concludes with recommendations for specialized training initiatives aimed at female entrepreneurs that address internalized constraints and barriers that keep women subservient and measures to shift gender and power beliefs. The outcome will benefit the stimulation of gender-specific public policies to develop a successful digital start-up ecosystem further.

Keywords: digital innovation, female digital entrepreneurs, feminist phenomenology, gender, marginalised communities

Procedia PDF Downloads 111
4200 An Investigation of Customer Relationship Management of Tourism

Authors: Wanida Suwunniponth

Abstract:

This research paper aimed to developing a causal relationship model of success factors of customer relationship management of tourism in Thailand and to investigating relationships among the potential factors that facilitate the success of customer relationship management (CRM). The research was conducted in both quantitative and qualitative methods, by utilizing both questionnaire and in-depth interview. The questionnaire was used in collecting the data from 250 management staff in the hotels located within Bangkok area. Sampling techniques used in this research included cluster sampling according to the service quality and simple random sampling. The data input was analyzed by use of descriptive analysis and System Equation Model (SEM). The research findings demonstrated important factors accentuated by most respondents towards the success of CRM, which were organization, people, information technology and the process of CRM. Moreover, the customer relationship management of tourism business in Thailand was found to be successful at a very significant level. The hypothesis testing showed that the hypothesis was accepted, as the factors concerning with organization, people and information technology played an influence on the process and the success of customer relationship management, whereas the process of customer relationship management factor manipulated its success. The findings suggested that tourism business in Thailand with the implementation of customer relationship management should opt in improvement approach in terms of managerial structure, corporate culture building with customer- centralized approach accentuated, and investment of information technology and customer analysis, in order to capacitate higher efficiency of customer relationship management process that would result in customer satisfaction and retention of service.

Keywords: customer relationship management, casual relationship model, tourism, Thailand

Procedia PDF Downloads 311
4199 Controlling the Process of a Chicken Dressing Plant through Statistical Process Control

Authors: Jasper Kevin C. Dionisio, Denise Mae M. Unsay

Abstract:

In a manufacturing firm, controlling the process ensures that optimum efficiency, productivity, and quality in an organization are achieved. An operation with no standardized procedure yields a poor productivity, inefficiency, and an out of control process. This study focuses on controlling the small intestine processing of a chicken dressing plant through the use of Statistical Process Control (SPC). Since the operation does not employ a standard procedure and does not have an established standard time, the process through the assessment of the observed time of the overall operation of small intestine processing, through the use of X-Bar R Control Chart, is found to be out of control. In the solution of this problem, the researchers conduct a motion and time study aiming to establish a standard procedure for the operation. The normal operator was picked through the use of Westinghouse Rating System. Instead of utilizing the traditional motion and time study, the researchers used the X-Bar R Control Chart in determining the process average of the process that is used for establishing the standard time. The observed time of the normal operator was noted and plotted to the X-Bar R Control Chart. Out of control points that are due to assignable cause were removed and the process average, or the average time the normal operator conducted the process, which was already in control and free form any outliers, was obtained. The process average was then used in determining the standard time of small intestine processing. As a recommendation, the researchers suggest the implementation of the standard time established which is with consonance to the standard procedure which was adopted from the normal operator. With that recommendation, the whole operation will induce a 45.54 % increase in their productivity.

Keywords: motion and time study, process controlling, statistical process control, X-Bar R Control chart

Procedia PDF Downloads 194
4198 Automatic Classification of Lung Diseases from CT Images

Authors: Abobaker Mohammed Qasem Farhan, Shangming Yang, Mohammed Al-Nehari

Abstract:

Pneumonia is a kind of lung disease that creates congestion in the chest. Such pneumonic conditions lead to loss of life of the severity of high congestion. Pneumonic lung disease is caused by viral pneumonia, bacterial pneumonia, or Covidi-19 induced pneumonia. The early prediction and classification of such lung diseases help to reduce the mortality rate. We propose the automatic Computer-Aided Diagnosis (CAD) system in this paper using the deep learning approach. The proposed CAD system takes input from raw computerized tomography (CT) scans of the patient's chest and automatically predicts disease classification. We designed the Hybrid Deep Learning Algorithm (HDLA) to improve accuracy and reduce processing requirements. The raw CT scans have pre-processed first to enhance their quality for further analysis. We then applied a hybrid model that consists of automatic feature extraction and classification. We propose the robust 2D Convolutional Neural Network (CNN) model to extract the automatic features from the pre-processed CT image. This CNN model assures feature learning with extremely effective 1D feature extraction for each input CT image. The outcome of the 2D CNN model is then normalized using the Min-Max technique. The second step of the proposed hybrid model is related to training and classification using different classifiers. The simulation outcomes using the publically available dataset prove the robustness and efficiency of the proposed model compared to state-of-art algorithms.

Keywords: CT scan, Covid-19, deep learning, image processing, lung disease classification

Procedia PDF Downloads 124
4197 Bioinformatic Design of a Non-toxic Modified Adjuvant from the Native A1 Structure of Cholera Toxin with Membrane Synthetic Peptide of Naegleria fowleri

Authors: Frida Carrillo Morales, Maria Maricela Carrasco Yépez, Saúl Rojas Hernández

Abstract:

Naegleria fowleri is the causative agent of primary amebic meningoencephalitis, this disease is acute and fulminant that affects humans. It has been reported that despite the existence of therapeutic options against this disease, its mortality rate is 97%. Therefore, the need arises to have vaccines that confer protection against this disease and, in addition to developing adjuvants to enhance the immune response. In this regard, in our work group, we obtained a peptide designed from the membrane protein MP2CL5 of Naegleria fowleri called Smp145 that was shown to be immunogenic; however, it would be of great importance to enhance its immunological response, being able to co-administer it with a non-toxic adjuvant. Therefore, the objective of this work was to carry out the bioinformatic design of a peptide of the Naegleria fowleri membrane protein MP2CL5 conjugated with a non-toxic modified adjuvant from the native A1 structure of Cholera Toxin. For which different bioinformatics tools were used to obtain a model with a modification in amino acid 61 of the A1 subunit of the CT (CTA1), to which the Smp145 peptide was added and both molecules were joined with a 13-glycine linker. As for the results obtained, the modification in CTA1 bound to the peptide produces a reduction in the toxicity of the molecule in in silico experiments, likewise, the prediction in the binding of Smp145 to the receptor of B cells suggests that the molecule is directed in specifically to the BCR receptor, decreasing its native enzymatic activity. The stereochemical evaluation showed that the generated model has a high number of adequately predicted residues. In the ERRAT test, the confidence with which it is possible to reject regions that exceed the error values was evaluated, in the generated model, a high score was obtained, which determines that the model has a good structural resolution. Therefore, the design of the conjugated peptide in this work will allow us to proceed with its chemical synthesis and subsequently be able to use it in the mouse meningitis protection model caused by N. fowleri.

Keywords: immunology, vaccines, pathogens, infectious disease

Procedia PDF Downloads 67
4196 Effectiveness of Parent Coaching Intervention for Parents of Children with Developmental Disabilities in the Home and Community

Authors: Elnaz Alimi, Keriakoula Andriopoulos, Sam Boyer, Weronika Zuczek

Abstract:

Occupational therapists can use coaching strategies to guide parents in providing therapy for their children with developmental disabilities. Evidence from various fields has shown increased parental self-efficacy and positive child outcomes as benefits of home and community-based parent coaching models. A literature review was conducted to investigate the effectiveness of parent coaching interventions delivered in home and community settings for children with developmental disabilities ages 0-12, on a variety of parent and child outcomes. CINAHL Plus, PsycINFO, PubMed, OTseeker were used as databases. The inclusion criteria consisted of: children with developmental disabilities ages 0-12 and their parents, parent coaching models conducted in the home and community, and parent and child outcomes. Studies were excluded if they were in a language other than English and published before 2000. Results showed that parent coaching interventions led to more positive therapy outcomes in child behaviors and symptoms related to their diagnosis or disorder. Additionally, coaching strategies had positive effects on parental satisfaction with therapy, parental self-efficacy, and family dynamics. Findings revealed decreased parental stress and improved parent-child relationships. Further research on parent coaching could involve studying the feasibility of coaching within occupational therapy specifically, incorporating cultural elements into coaching, qualitative studies on parental satisfaction with coaching, and measuring the quality of life outcomes for the whole family.

Keywords: coaching model, developmental disabilities, occupational therapy, pediatrics

Procedia PDF Downloads 170
4195 Software Development to Empowering Digital Libraries with Effortless Digital Cataloging and Access

Authors: Abdul Basit Kiani

Abstract:

The software for the digital library system is a cutting-edge solution designed to revolutionize the way libraries manage and provide access to their vast collections of digital content. This advanced software leverages the power of technology to offer a seamless and user-friendly experience for both library staff and patrons. By implementing this software, libraries can efficiently organize, store, and retrieve digital resources, including e-books, audiobooks, journals, articles, and multimedia content. Its intuitive interface allows library staff to effortlessly manage cataloging, metadata extraction, and content enrichment, ensuring accurate and comprehensive access to digital materials. For patrons, the software offers a personalized and immersive digital library experience. They can easily browse the digital catalog, search for specific items, and explore related content through intelligent recommendation algorithms. The software also facilitates seamless borrowing, lending, and preservation of digital items, enabling users to access their favorite resources anytime, anywhere, on multiple devices. With robust security features, the software ensures the protection of intellectual property rights and enforces access controls to safeguard sensitive content. Integration with external authentication systems and user management tools streamlines the library's administration processes, while advanced analytics provide valuable insights into patron behavior and content usage. Overall, this software for the digital library system empowers libraries to embrace the digital era, offering enhanced access, convenience, and discoverability of their vast collections. It paves the way for a more inclusive and engaging library experience, catering to the evolving needs of tech-savvy patrons.

Keywords: software development, empowering digital libraries, digital cataloging and access, management system

Procedia PDF Downloads 51
4194 Challenges of Implementing Participatory Irrigation Management for Food Security in Semi Arid Areas of Tanzania

Authors: Pilly Joseph Kagosi

Abstract:

The study aims at assessing challenges observed during the implementation of participatory irrigation management (PIM) approach for food security in semi-arid areas of Tanzania. Data were collected through questionnaire, PRA tools, key informants discussion, Focus Group Discussion (FGD), participant observation, and literature review. Data collected from the questionnaire was analysed using SPSS while PRA data was analysed with the help of local communities during PRA exercise. Data from other methods were analysed using content analysis. The study revealed that PIM approach has a contribution in improved food security at household level due to the involvement of communities in water management activities and decision making which enhanced the availability of water for irrigation and increased crop production. However, there were challenges observed during the implementation of the approach including; minimum participation of beneficiaries in decision-making during planning and designing stages, meaning inadequate devolution of power among scheme owners. Inadequate and lack of transparency on income expenditure in Water Utilization Associations’ (WUAs), water conflict among WUAs members, conflict between farmers and livestock keepers and conflict between WUAs leaders and village government regarding training opportunities and status; WUAs rules and regulation are not legally recognized by the National court and few farmers involved in planting trees around water sources. However, it was realized that some of the mentioned challenges were rectified by farmers themselves facilitated by government officials. The study recommends that the identified challenges need to be rectified for farmers to realize impotence of PIM approach as it was realized by other Asian countries.

Keywords: challenges, participatory approach, irrigation management, food security, semi arid areas

Procedia PDF Downloads 309
4193 Application of Griddization Management to Construction Hazard Management

Authors: Lingzhi Li, Jiankun Zhang, Tiantian Gu

Abstract:

Hazard management that can prevent fatal accidents and property losses is a fundamental process during the buildings’ construction stage. However, due to lack of safety supervision resources and operational pressures, the conduction of hazard management is poor and ineffective in China. In order to improve the quality of construction safety management, it is critical to explore the use of information technologies to ensure that the process of hazard management is efficient and effective. After exploring the existing problems of construction hazard management in China, this paper develops the griddization management model for construction hazard management. First, following the knowledge grid infrastructure, the griddization computing infrastructure for construction hazards management is designed which includes five layers: resource entity layer, information management layer, task management layer, knowledge transformation layer and application layer. This infrastructure will be as the technical support for realizing grid management. Second, this study divides the construction hazards into grids through city level, district level and construction site level according to grid principles. Last, a griddization management process including hazard identification, assessment and control is developed. Meanwhile, all stakeholders of construction safety management, such as owners, contractors, supervision organizations and government departments, should take the corresponding responsibilities in this process. Finally, a case study based on actual construction hazard identification, assessment and control is used to validate the effectiveness and efficiency of the proposed griddization management model. The advantage of this designed model is to realize information sharing and cooperative management between various safety management departments.

Keywords: construction hazard, griddization computing, grid management, process

Procedia PDF Downloads 249
4192 Co-payment Strategies for Chronic Medications: A Qualitative and Comparative Analysis at European Level

Authors: Pedro M. Abreu, Bruno R. Mendes

Abstract:

The management of pharmacotherapy and the process of dispensing medicines is becoming critical in clinical pharmacy due to the increase of incidence and prevalence of chronic diseases, the complexity and customization of therapeutic regimens, the introduction of innovative and more expensive medicines, the unbalanced relation between expenditure and revenue as well as due to the lack of rationalization associated with medication use. For these reasons, co-payments emerged in Europe in the 70s and have been applied over the past few years in healthcare. Co-payments lead to a rationing and rationalization of user’s access under healthcare services and products, and simultaneously, to a qualification and improvement of the services and products for the end-user. This analysis, under hospital practices particularly and co-payment strategies in general, was carried out on all the European regions and identified four reference countries, that apply repeatedly this tool and with different approaches. The structure, content and adaptation of European co-payments were analyzed through 7 qualitative attributes and 19 performance indicators, and the results expressed in a scorecard, allowing to conclude that the German models (total score of 68,2% and 63,6% in both elected co-payments) can collect more compliance and effectiveness, the English models (total score of 50%) can be more accessible, and the French models (total score of 50%) can be more adequate to the socio-economic and legal framework. Other European models did not show the same quality and/or performance, so were not taken as a standard in the future design of co-payments strategies. In this sense, we can see in the co-payments a strategy not only to moderate the consumption of healthcare products and services, but especially to improve them, as well as a strategy to increment the value that the end-user assigns to these services and products, such as medicines.

Keywords: clinical pharmacy, co-payments, healthcare, medicines

Procedia PDF Downloads 226
4191 Growth and Yield Potential of Quinoa genotypes on Salt Affected Soils

Authors: Shahzad M. A. Basra, Shahid Iqbal, Irfan Afzal, Hafeez-ur-Rehman

Abstract:

Quinoa a facultative halophyte crop plant is a new introduction in Pakistan due to its superior nutritional profile and its abiotic stress tolerance, especially against salinity. Present study was conducted to explore halophytic behavior of quinoa. Four quinoa genotypes (A1, A2, A7 and A9) were evaluated against high salinity (control, 100, 200, 300 and 400 mM). Evaluation was made on the basis of ionic analysis (Na+, K+ and K+: Na+ ratio in shoot) and root- shoot fresh and dry weight at four leaf stage. Seedling growth i.e. fresh and dry weight of shoot and root increased by 100 mM salinity and then growth decreased gradually with increasing salinity level in all geno types. Mineral analysis indicated that A2 and A7 have more tolerant behavior having low Na+ and high K+ ¬concentration as compared to A1 and A9. Same geno types as above were also evaluated against high salinity (control, 10, 20, 30, and 40 dS m-1) in pot culture during 2012-13. It was found that increase in salinity up to 10 dS m-1 the plant height, stem diameter and yield related traits increased but decreased with further increase in salinity. Same trend was observed in ionic contents. Maximum grain yield was achieved by A7 (100 g plant-1) followed by A2 (82 g plant-1) at salinity level 10 dS m-1. Next phase was carried out through field settings by using salt tolerant geno types (A2 and A7) at Crop Physiology Research Area Farm (non saline soil as control)/ Proka Farm (salt affected with EC up to 15 dS m-1), University of Agriculture, Faisalabad and Soil Salinity Research Institute, Pindi Bhtiaan (SSRI) Farm (one normal as control and two salt affected fields with EC values up to 15 and 30 dS m-1) during 2013-14. Genotype A7 showed maximum growth and gave maximum yield (3200 kg ha-1) at Proka Farm which was statistically at par to the values of yield obtained on normal soils of Faisalabad. Geno type A7 also gave maximum yield 2800 kg ha-1 on normal field of Pindi bhtiaan followed by as obtained (2340) on salt problem field (15 dS m-1) of same location.

Keywords: quinoa, salinity, halophyte, genotype

Procedia PDF Downloads 547
4190 In Vitro and in Vivo Evaluation of Nano Collagen Molecules to Enhance Mesenchymal Stem Cells Differentiate into Insulin Producing Cells

Authors: Chin-Tsu Ma, Yi-Jhen Wu, Hsia Ying Cheng, Han Hsiang Huang, Shyh Ming Kuo

Abstract:

The use of specific molecules including nutrients and pharmacological agents has been tried in modulation of stem cells differentiation (MSCs) to insulin producing cells. The aim of this study is to investigate the ability of nano collagen molecules (nutrient or scaffold) to enhance the MSCs differentiation into insulin-producing cells in combination with nicotinamide and exendin-4 (pharmacological agents) in vitro and in vivo. The results demonstrated that the cells exhibit morphologically islet-like clusters after treatment with nano collagen molecules, nicotinamide and exendin-4. MSCs extra treated with nano collagen molecules showed significant increases in Nkx6.1 and insulin mRNA expression at 14-d and 21-d culture compared with those merely treated with nicotinamide and exendin-4. Early 7-day elevation in PDX-1 mRNA expression was observed. Furthermore, the MSCs exposed to nano collagen molecules produced the highest secretion of insulin (p < 0.05). Type-2 diabetes induced by high-fat diet and low dose of streptozotocin in rat model was built in this study. This rat exhibited higher food intake, water intake, lower glucose tolerance, lower-insulin tolerance, and higher HbA1C (significant increases, p < 0.01) as compared with the normal rat that demonstrated the model of type-2 diabetes was successfully built. Biopsy examinations also showed that obvious destruction of islet. After injection of differentiated MSCs into the destructed pancreas of diabetes rat, more regenerated islet were observed at the rats that treated with nano collagen molecules and exhibited much lower HbA1C as compared with the normal rat and diabetes rat after 4 weeks (significant deceases, p < 0.001). These results indicate that the culturing MSCs with nano collagen molecules, nicotinamide, and exendin-4 are beneficial for MSCs differentiation into islet-like cells. These nano collagen molecules may lead to alternations or up-regulation of gene expression and influence the differentiated outcomes induced by nicotinamide and exendin-4.

Keywords: nano collagen molecules, nicotinamide, MSCs, diabetes

Procedia PDF Downloads 392
4189 Dynamic Response around Inclusions in Infinitely Inhomogeneous Media

Authors: Jinlai Bian, Zailin Yang, Guanxixi Jiang, Xinzhu Li

Abstract:

The problem of elastic wave propagation in inhomogeneous medium has always been a classic problem. Due to the frequent occurrence of earthquakes, many economic losses and casualties have been caused, therefore, to prevent earthquake damage to people and reduce damage, this paper studies the dynamic response around the circular inclusion in the whole space with inhomogeneous modulus, the inhomogeneity of the medium is reflected in the shear modulus of the medium with the spatial position, and the density is constant, this method can be used to solve the problem of the underground buried pipeline. Stress concentration phenomena are common in aerospace and earthquake engineering, and the dynamic stress concentration factor (DSCF) is one of the main factors leading to material damage, one of the important applications of the theory of elastic dynamics is to determine the stress concentration in the body with discontinuities such as cracks, holes, and inclusions. At present, the methods include wave function expansion method, integral transformation method, integral equation method and so on. Based on the complex function method, the Helmholtz equation with variable coefficients is standardized by using conformal transformation method and wave function expansion method, the displacement and stress fields in the whole space with circular inclusions are solved in the complex coordinate system, the unknown coefficients are solved by using boundary conditions, by comparing with the existing results, the correctness of this method is verified, based on the superiority of the complex variable function theory to the conformal transformation, this method can be extended to study the inclusion problem of arbitrary shapes. By solving the dynamic stress concentration factor around the inclusions, the influence of the inhomogeneous parameters of the medium and the wavenumber ratio of the inclusions to the matrix on the dynamic stress concentration factor is analyzed. The research results can provide some reference value for the evaluation of nondestructive testing (NDT), oil exploration, seismic monitoring, and soil-structure interaction.

Keywords: circular inclusions, complex variable function, dynamic stress concentration factor (DSCF), inhomogeneous medium

Procedia PDF Downloads 119