Search results for: full adders

Authors: Sulaiman Al amro, Ali Alkhalifah

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The growing number of computer viruses and the detection of zero day malware have been the concern for security researchers for a large period of time. Existing antivirus products (AVs) rely on detecting virus signatures which do not provide a full solution to the problems associated with these viruses. The use of logic formulae to model the behaviour of viruses is one of the most encouraging recent developments in virus research, which provides alternatives to classic virus detection methods. In this paper, we proposed a comparative study about different virus detection techniques. This paper provides the advantages and drawbacks of different detection techniques. Different techniques will be used in this paper to provide a discussion about what technique is more effective to detect computer viruses.

Keywords: computer viruses, virus detection, signature-based, behaviour-based, heuristic-based

Procedia PDF Downloads 486

Authors: Yuexi Xiong, Jingwu He

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The structural components in an energy facility such as steam turbine machines are operated under high stress and elevated temperature in an endured time period and thus the creep deformation and creep rupture failure are important issues that need to be addressed in the design of such components. There are numerous creep models being used for creep analysis that have both advantages and disadvantages in terms of accuracy and efficiency. The Isochronous Creep Analysis is one of the simplified approaches in which a full-time dependent creep analysis is avoided and instead an elastic-plastic analysis is conducted at each time point. This approach has been established based on the rupture dependent creep equations using the well-known Larson-Miller parameter. In this paper, some fundamental aspects of creep deformation and the rupture dependent creep models are reviewed and the analysis procedures using isochronous creep curves are discussed. Four rupture failure criteria are examined from creep fundamental perspectives including criteria of Stress Damage, Strain Damage, Strain Rate Damage, and Strain Capability. The accuracy of these criteria in predicting creep life is discussed and applications of the creep analysis procedures and failure predictions of simple models will be presented. In addition, a new failure criterion is proposed to improve the accuracy and effectiveness of the existing criteria. Comparisons are made between the existing criteria and the new one using several examples materials. Both strain increase and stress relaxation form a full picture of the creep behaviour of a material under high temperature in an endured time period. It is important to bear this in mind when dealing with creep problems. Accordingly there are two sets of rupture dependent creep equations. While the rupture strength vs LMP equation shows how the rupture time depends on the stress level under load controlled condition, the strain rate vs rupture time equation reflects how the rupture time behaves under strain-controlled condition. Among the four existing failure criteria for rupture life predictions, the Stress Damage and Strain Damage Criteria provide the most conservative and non-conservative predictions, respectively. The Strain Rate and Strain Capability Criteria provide predictions in between that are believed to be more accurate because the strain rate and strain capability are more determined quantities than stress to reflect the creep rupture behaviour. A modified Strain Capability Criterion is proposed making use of the two sets of creep equations and therefore is considered to be more accurate than the original Strain Capability Criterion.

Keywords: creep analysis, high temperature mateials, rapture evalution, steam turbine machines

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Authors: S. Chaudhuri, P. A. Bhobe

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Fe₂TiSn is a non-magnetic full Heusler alloy with a small gap (~ 0.07 eV) at the Fermi level. The electronic structure is highly symmetric in both the spin bands and a small percentage of substitution of holes or electrons can push the system towards spin polarization. A stable 100% spin polarization or half-metallicity is very desirable in the field of spintronics, making Fe₂TiSn a highly attractive material. However, this composition suffers from an inherent anti-site disorder between Fe and Ti sites. This paper reports on the method adopted to control the anti-site disorder and the realization of the half-metallic ground state in Fe₂TiSn, achieved by chemical substitution. Here, Sb was substituted at Sn site to obtain Fe₂TiSn₁₋ₓSbₓ compositions with x = 0, 0.1, 0.25, 0.5 and 0.6. All prepared compositions with x ≤ 0.6 exhibit long-range L2₁ ordering and a decrease in Fe – Ti anti-site disorder. The transport and magnetic properties of Fe₂TiSn₁₋ₓSbₓ compositions were investigated as a function of temperature in the range, 5 K to 400 K. Electrical resistivity, magnetization, and Hall voltage measurements were carried out. All the experimental results indicate the presence of the half-metallic ground state in x ≥ 0.25 compositions. However, the value of saturation magnetization is small, indicating the presence of compensated magnetic moments. The observed magnetic moments' values are in close agreement with the Slater–Pauling rule in half-metallic systems. Magnetic interactions in Fe₂TiSn₁₋ₓSbₓ are understood from the local crystal structural perspective using extended X-ray absorption fine structure (EXAFS) spectroscopy. The changes in bond distances extracted from EXAFS analysis can be correlated with the hybridization between constituent atoms and hence the RKKY type magnetic interactions that govern the magnetic ground state of these alloys. To complement the experimental findings, first principle electronic structure calculations were also undertaken. The spin-polarized DOS complies with the experimental results for Fe₂TiSn₁₋ₓSbₓ. Substitution of Sb (an electron excess element) at Sn–site shifts the majority spin band to the lower energy side of Fermi level, thus making the system 100% spin polarized and inducing long-range magnetic order in an otherwise non-magnetic Fe₂TiSn. The present study concludes that a stable half-metallic system can be realized in Fe₂TiSn with ≥ 50% Sb – substitution at Sn – site.

Keywords: antisite disorder, EXAFS, Full Heusler alloy, half metallic ferrimagnetism, RKKY interactions

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Authors: Hyoup-Sang Yoon

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The quality of video transmitted by mobile ad hoc networks (MANETs) can be influenced by several factors, including protocol layers; parameter settings of each protocol. In this paper, we are concerned with understanding the functional relationship between these influential factors and objective video quality in MANETs. We illustrate a systematic statistical design of experiments (DOE) strategy can be used to analyse MANET parameters and performance. Using a 2k factorial design, we quantify the main and interactive effects of 7 factors on a response metric (i.e., mean opinion score (MOS) calculated by PSNR with Evalvid package) we then develop a first-order linear regression model between the influential factors and the performance metric.

Keywords: evalvid, full factorial design, mobile ad hoc networks, ns-2

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Authors: Zahra Karimi

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The purpose of this paper is to investigate the role and importance of accounting for the implementation of the VAT system in the country. For this purpose, after the evaluation of specifications and important advantages of the VAT and the experience of other countries, important role of accounting in the precise determination of taxes, strategies to prevent escape of tax and realization of tax revenues of government, necessary control to increase the efficiency and accuracy of the calculations discussed. High-dependence of government to borrowing from the banking system and inflation tax and a low general ratio of tax revenues to GDP, indicating the inadequacy of the country's tax system. It can be said that being of a proper accounting system consider as a prerequisite for successful implementation of VAT in the country. So it's crucial for accountants with responsibility announce its full fitness to meet the requirements. For successful implementation of VAT as such a multi-stage sales tax and the tax on the price.

Keywords: accounting, tax reform in Iran, Value Added Tax (VAT), economic

Procedia PDF Downloads 387

Authors: Hee Joon Lee

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There are many difficulties in measuring a small flow rate of an order of milli grams per minute (LPM) or less using a conventional flowmeter. Therefore, a flow meter with minimal loss and based on a new concept was designed as part of this paper. A chamber was manufactured with a level transmitter and an on-off control valve. When the level of the collected condensed water reaches the top of the chamber, the valve opens to allow the collected water to drain back into the tank. To allow the water to continue to drain when the signal is lost, the valve is held open for a few seconds by a time delay switch and then closed. After an examination, the condensing flow rate was successfully measured with the uncertainty of ±5.7% of the full scale for the chamber.

Keywords: chamber, condensation, flow meter, milli-grams

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Authors: Irina Belozerova

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In the recent years, the number of crimes against peace and humanity has constantly been increasing. The development of the international community is inseparably connected to the compliance with the law which protects the rights and interests of citizens in all of their manifestations. The provisions of the law of criminal procedure are no exception. The rights of the victims of genocide, of the war crimes and the crimes against humanity, require particular attention. These crimes fall within the jurisdiction of the International Criminal Court governed by the Rome Statute of the International Criminal Court. These crimes have the following features. First, any such crime has a mass character and therefore requires specific regulation in the international criminal law and procedure and the national criminal law and procedure of different countries. Second, the victims of such crimes are usually children, women and old people; the entire national, ethnic, racial or religious groups are destroyed. These features influence the classification of victims by the age criterion. Article 68 of the Rome Statute provides for protection of the safety, physical and psychological well-being, dignity and privacy of victims and witnesses and thus determines the procedural status of these persons. However, not all the persons whose rights have been violated by the commission of these crimes acquire the status of victims. This is due to the fact that such crimes affect a huge number of persons and it is impossible to mention them all by name. It is also difficult to assess the entire damage suffered by the victims. While assessing the amount of damages it is essential to take into account physical and moral harm, as well as property damage. The procedural status of victims thus gains an exclusive character. In order to determine the full extent of the damage suffered by the victims it is necessary to collect sufficient evidence. However, it is extremely difficult to collect the evidence that would ensure the full and objective protection of the victims’ rights. While making requests for the collection of evidence, the International Criminal Court faces the problem of protection of national security information. Religious beliefs and the family life of victims are of great importance. In some Islamic countries, it is impossible to question a woman without her husband’s consent which affects the objectivity of her testimony. Finally, the number of victims is quantified by hundreds and thousands. The assessment of these elements demands time and highly qualified work. These factors justify the creation of a mechanism that would help to collect the evidence and establish the truth in the international criminal proceedings. This mechanism will help to impose a just and appropriate punishment for the persons accused of having committed a crime, since, committing the crime, criminals could not misunderstand the outcome of their criminal intent.

Keywords: crimes against humanity, evidence in international criminal proceedings, international criminal proceedings, protection of victims

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Authors: Hani Alkayed, Belal Omar, Eileen Roddy

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This study focuses on investigating the determinants of Corporate Social Responsibility Disclosure (CSRD) extent and quality in Jordan. The study examines factors that influence CSR disclosure extent and quality, such as corporate characteristics (size, gearing, firm’s age, and industry type), corporate governance (board size, number of meetings, non-executive directors, female directors in the board, family directors in the board, foreign members, audit committee, type of external auditors, and CEO duality) and ownership structure (government ownership, institutional ownership, and ownership concentration). Legitimacy theory is utilised as the main theory for our theoretical framework. A quantitative approach is adopted for this research and content analysis technique is used to gather CSR disclosure extent and quality from the annual reports. The sample is withdrawn from the annual reports of 118 Jordanian companies over the period of 2010-2015. A CSRD index is constructed, and includes the disclosures of the following categories; environmental, human resources, product and consumers, and community involvement. A 7 point-scale measurement was developed to examine the quality of disclosure, were 0= No Disclosures, 1= General disclosures, (Non-monetary), 2= General disclosures, (Non-monetary) with pictures, charts, and graphs 3= Descriptive/ qualitative disclosures, specific details (Non-monetary), 4= Descriptive/ qualitative disclosures, specific details with pictures, charts, and graphs, 5= Numeric disclosures, full descriptions with supporting numbers, 6= Numeric disclosures, full descriptions with supporting numbers, pictures, and Charts. This study fills the gap in the literature regarding CSRD in Jordan, and the fact that all the previous studies have ignored a clear categorisation as a measurement of quality. The result shows that the extent of CSRD is higher than the quality in Jordan. Regarding the determinants of CSR disclosures, the followings were found to have a significant relationship with both extent and quality of CSRD except non-executives, were the significant relationship was found just with the extent of CSRD: board size, non-executive directors, firm’s age, foreign members on the board, number of boards meetings, the presence of audit committees, big 4, government ownership, firm’s size, industry type.

Keywords: content analysis, corporate governance, corporate social responsibility disclosure, Jordan, quality of disclosure

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Authors: Jo Rhodes, Peter Lok, Zahra Sadeghinejad

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The aim of this study is to determine the impact of metacognition on top management team members and firm performance based on full team integration. A survey of 1500 small to medium enterprises (SMEs) was initiated and 140 firms were obtained in this study (with response rate of 9%). The result showed that different metacognitive abilities of managers [knowledge and experience] could enhance team decision-making and problem solving, resulting in greater firm performance. This is a significant finding for SMEs because these organisations have small teams with owner leadership and entrepreneurial orientation.

Keywords: metacognition, behavioural integration, top management team (TMT), performance

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Authors: Fatima Mokeddem

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The phonocardiogram signal (PCG) is a physiological signal that reflects heart mechanical activity, is a promising tool for curious researchers in this field because it is full of indications and useful information for medical diagnosis. PCG segmentation is a basic step to benefit from this signal. Therefore, this paper presents an algorithm that serves the separation of heart sounds and heart murmurs in case they exist in order to use them in several applications and heart sounds analysis. The separation process presents here is founded on three essential steps filtering, envelope detection, and heart sounds segmentation. The algorithm separates the PCG signal into S1 and S2 and extract cardiac murmurs.

Keywords: phonocardiogram signal, filtering, Envelope, Detection, murmurs, heart sounds

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Authors: Zhao Bin, Yan Dan Lei

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In this paper, a multi-pattern parallel PRBS generator and a dedicated parallel BER tester is proposed for the 8-Gbps On-chip interconnection testing. A unique full-parallel PRBS checker is also proposed. The proposed design, together with the custom-designed high-speed parallel-to-serial and the serial-to-parallel circuit, will be used to test different on-chip interconnection transceivers. The design is implemented in TSMC 28nm CMOS technology with working voltage at 1.0 V. The serial to parallel ratio is 8:1 so the parallel PRBS generation and BER Tester can be run at lower speed.

Keywords: PRBS, BER, high speed, generator

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Authors: André Lages, Victor Dmitriev, Juliano Bazzo, Gianni Portela

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This work evaluates the feasibility of the graphene application to perform as a wideband reconfigurable material for lens antennas in 5G/6G and satellite applications. Based on transformation optics principles, the electromagnetic waves can be efficiently guided by modifying the effective refractive index. Graphene behavior can range between a lossy dielectric and a good conductor due to the variation of its chemical potential bias, thus arising as a promising solution for electromagnetic devices. The graphene properties and a lens antenna comprising multiples layers and periodic arrangements of graphene patches were analyzed using full-wave simulations. A dipole directivity was improved from 7 to 18.5 dBi at 29 GHz. In addition, the realized gain was enhanced 7 dB across a 14 GHz bandwidth within the Ka/5G band.

Keywords: 5G/6G, graphene, lens, reconfigurable, satellite

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Authors: Maitham Al-Safwani

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Motor vibration issues were analyzed by several studies. It is generally accepted that vibration issues result from poor equipment installation. We had a water injection pump tested in the factory and exceeded the pump the vibration limit. Once the pump was brought to the site, its half-size shim plates were replaced with full-size shims plates that drastically reduced the vibration. In this study, vibration data was recorded for several similar motors run at the same and different speeds. The vibration values were recorded -for two and a half hours- and the vibration readings were analyzed to determine when the readings became consistent. This was as well supported by recording the audio noises produced by some machines seeking a relationship between changes in machine noises and machine abnormalities, such as vibration.

Keywords: vibration, noise, installation, machine

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Authors: Larissa Kamdjong

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The purpose of this research is to introduce inclusive leadership as a distinct theoretical framework to understand its meaning and functions in advancing gender equality and empowerment in public relations leadership. By proposing women inclusive leadership theoretical model, we explored the roles of inclusive leadership in fostering an organization’s diverse climate and facilitating its practice of participative leadership in empowering women in public relations to reach their full potential in leadership advancement. Moreover, our results confirmed both direct and indirect impacts inclusive leadership could have on women’s perceptions of continued career growth opportunities. Our findings provide theoretical implications and practical solutions to address women’s leadership challenges through an inclusive leadership lens.

Keywords: inclusiveness, empowerment, leadership, career opportunities

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Authors: Matthew Montebello

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Student engagement within a virtual learning environment generates masses of data points that can significantly contribute to the learning analytics that lead to decision support. Ideally, similar data is collected during student interaction with a physical learning space, and as a consequence, data is present at a large scale, even in relatively small classes. In this paper, we report of such an occurrence during classes held in a HiFlex modality as we investigate the advantages of adopting such a methodology. We plan to take full advantage of the learner-generated data in an attempt to further enhance the effectiveness of the adopted learning environment. This could shed crucial light on operating modalities that higher education institutions around the world will switch to in a post-COVID era.

Keywords: HiFlex, big data in higher education, learning analytics, virtual learning environment

Procedia PDF Downloads 201

Authors: Ira V. Stancheva, Ely G. Zayova, Maria P. Geneva, Marieta G. Hristozkova, Lyudmila I. Dimitrova, Maria I. Petrova

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The study describes a highly efficient and low-cost protocol for rapid and mass in vitro propagation of medicinal and aromatic plant species (Hyssopus officinalis L., Lamiaceae). Hyssop is an important aromatic herb used for its medicinal values because of its antioxidant, anti-inflammatory and antimicrobial properties. The protocol for large-scale multiplication of this aromatic plant was developed using young stem tips explants. The explants were sterilized with 0.04% mercuric chloride (HgCl₂) solution for 20 minutes and washing three times with sterile distilled water in 15 minutes. The cultural media was full and half strength Murashige and Skoog medium containing indole-3-butyric acid. Full and ½ Murashige and Skoog media without auxin were used as controls. For each variant 20 glass tubes with two plants were used. In each tube two tip and nodal explants were inoculated. Maximum shoot and root number were obtained on ½ Murashige and Skoog medium supplemented with 0.1 mg L-1 indole-3-butyric acid at the same time after four weeks of culture. The number of shoots per explant and shoot height were considered. The data on rooting percentage, the number of roots per plant and root length were collected after the same cultural period. The highest percentage of survival 85% for this medicinal plant was recorded in mixture of soil, sand and perlite (2:1:1 v/v/v). This mixture was most suitable for acclimatization of all propagated plants. Ex vitro acclimatization was carried out at 24±1 °C and 70% relative humidity under 16 h illuminations (50 μmol m⁻²s⁻¹). After adaptation period, the all plants were transferred to the field. The plants flowered within three months after transplantation. Phenotypic variations in the acclimatized plants were not observed. An average of 90% of the acclimatized plants survived after transferring into the field. All the in vitro propagated plants displayed normal development under the field conditions. Developed in vitro techniques could provide a promising alternative tool for large-scale propagation that increases the number of homologous plants for field cultivation. Acknowledgments: This study was conducted with financial support from National Science Fund at the Bulgarian Ministry of Education and Science, Project DN06/7 17.12.16.

Keywords: Hyssopus officinalis L., in vitro culture, micro propagation, acclimatization

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Authors: Lisdey Espinoza Pedraza

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Organised crime in Mexico evolves faster that our capacity to understand and explain it. Organised gangs have become successful entrepreneurs in many ways ad they have somehow mimicked the working ways of the authorities and in many cases, they have successfully infiltrated the governmental spheres. This business model is only possible under a clear scheme of rampant impunity. Impunity, however, is not exclusive to the PRI. Nor the PRI, PAN, or PRD can claim the monopoly of corruption, but what is worse is that none can claim full honesty in their acts either. The current security crisis in Mexico shows a crisis in the Mexican political party system. Corruption today is not only a problem of dishonesty and the correct use of public resources. It is the principal threat to Mexican democracy, governance, and national security.

Keywords: security, war on drugs, drug trafficking, Mexico, Latin America, United States

Procedia PDF Downloads 418

Authors: Saradiya Mukherjee

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Background: Indian Muslims, compared to their counterparts in other religions, generally do not fare well on many yardsticks related to socio-economic progress and the same is true with maternal health care utilization. Due to low age at marriage a major percentage of child birth is ascribed to young (15-24 years) Muslim mothers in, which pose serious concerns on the maternal health care of Young Married Muslim women (YMMW). A thorough search of past literature on Muslim women’s health and health care reveals that studies in India have mainly focused on religious differences in fertility levels and contraceptive use while the research on the determinants of maternal health care utilization among Muslim women are lacking in India. Data and Methods: Retrieving data from the National Family Health Survey -3 (2005-06) this study attempts to assess the level of utilization and factors effecting three key maternal health indicators (full ANC, safe delivery and PNC) among YMMW (15-24 years) in India. The key socio-economic and demographic variables taken as independent or predictor variables in the study was guided by existing literature particularly for India. Bi-variate analysis and chi square test was applied and variables which were found to be significant were further included in binary logistic regression. Results: The findings of the study reveal abysmally low levels of utilization for all three indicators i.e. full ANC, safe delivery and PNC of maternal health care included in the study. Mother’s education, mass media exposure, women’s autonomy, birth order, economic status wanted status of child and region of residence were found to be significant variables effecting maternal health care utilization among YMMW. Multivariate analysis reveals that no mass media exposure, lower autonomy, education, poor economic background, higher birth order and unintended pregnancy are some of the reasons behind low maternal health care utilization. Conclusion: Considering the low level of safe maternal health care utilization and its proximate determinants among YMMW the study suggests educating Muslim girls, promoting family planning use, involving media and collaboration between religious leader and health care system could be some important policy level interventions to address the unmet need of maternity services among YMMW.

Keywords: young Muslim women, religion, socio-economic condition, antenatal care, delivery, post natal care

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Authors: Kaddour Fellague Mohammed

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The world has seen in recent years, significant developments affected various aspects of life and influenced the different types of institutions, thus was born a new world is a world of globalization, which dominated the scientific revolution and the tremendous technological developments, and that contributed to the re-formation of human resources in contemporary organizations, and made patterns new regulatory and at the same time raised and strongly values and new ideas, the organizations have become more flexible, and faster response to consumer and environmental conditions, and exceeded the problem of time and place in the framework of communication and human interaction and use of advanced information technology and adoption mainly mechanism in running its operations , focused on performance and based strategic thinking and approach in order to achieve its strategic goals high degrees of superiority and excellence, this new reality created an increasing need for a new type of human resources, quality aims to renew and aspire to be a strategic player in managing the organization and drafting of various strategies, think globally and act locally, to accommodate local variables in the international markets, which began organizations tend to strongly as well as the ability to work under different cultures. Human resources management of the most important management functions to focus on the human element, which is considered the most valuable resource of the Department and the most influential in productivity at all, that the management and development of human resources Tattabra a cornerstone in the majority of organizations which aims to strengthen the organizational capacity, and enable companies to attract and rehabilitation of the necessary competencies and are able to keep up with current and future challenges, human resources can contribute to and strongly in achieving the objectives and profit organization, and even expand more than contribute to the creation of new jobs to alleviate unemployment and achieve full operation, administration and human resources mean short optimal use of the human element is available and expected, where he was the efficiency and capabilities, and experience of this human element, and his enthusiasm for the work stop the efficiency and success in reaching their goals, so interested administration scientists developed the principles and foundations that help to make the most of each individual benefit in the organization through human resources management, these foundations start of the planning and selection, training and incentives and evaluation, which is not separate from each other, but are integrated with each other as a system systemic order to reach the efficient functioning of the human resources management and has been the organization as a whole in the context of development sustainable.

Keywords: configuration, training, development, human resources, operating

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Authors: B. Bouadjemi, S. Bentata, T. Lantri, Souidi Amel, W.Bensaali, A. Zitouni, Z. Aziz

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We performed first-principle calculations, the full-potential linearized augmented plane wave (FP-LAPW) method is used to calculate structural, optoelectronic and magnetic properties of cubic halide perovskites CsPbX3 (X= F,I). We employed for this study the GGA approach and for exchange is modeled using the modified Becke-Johnson (mBJ) potential to predicting the accurate band gap of these materials. The optical properties (namely: the real and imaginary parts of dielectric functions, optical conductivities and absorption coefficient absorption make this halide perovskites promising materials for solar cells applications.

Keywords: halide perovskites, mBJ, solar cells, FP-LAPW, optoelectronic properties, absorption coefficient

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Authors: Faris Alghamdi

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Identifying which conflict management styles organizational members prefer, and what variables influence these selections, is an essential component of organizational conflict management as well as human resource management, particularly in training and development strategies. This study aims to examine the relationship between work experience and preferred conflict management styles. Utilizing the Rahim Organizational Conflict Inventory- II Form C, data were collected from 109 full-time employees of various organizations in the Eastern province of Saudi Arabia. The Pearson’s correlation coefficient analysis showed a statistically significant relationship between the integrating conflict management style and the length of work experience. Nevertheless, this relationship was negative, not positive as hypothesized.

Keywords: conflict management style, organizational members, work experience

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Authors: Runlang Zhu, Weijun Gao, Yinqi Zhang, Gangwei Cai

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In order to deal with issues such as the environmental problems and aging of the population, the Japanese government wanted to achieve goals like 'a city where everyone wants to live' and 'a city full of energy for everyone' by creating environmental, social, and economic values in the process of urban development. They began to promote the concept of 'Environmental Future City' in 2010, aiming to create cities and regions with excellent environments, sustainable economic development, and social systems. After taking a look at the history, concept, and development of environmental future cities, the paper will discuss the evaluation system of them, introduce representative cases, and point out what other cities can learn from their development process.

Keywords: environmental future city, city concept, CASBEE, environmental performance assessment

Procedia PDF Downloads 157

Authors: Susana Gonçalves, Joana Lencart, Anabela Gregório Dias

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Introduction: In combination with chemotherapy, Total Body Irradiation (TBI) is most used as part of the conditioning regimen prior to allogeneic hematopoietic stem cell transplantation. Conventional TBI techniques have a long application time but non-conformality of beam-application with the inability to individually spare organs at risk. Our institution’s intention is to start using Volumetric Modulated Arc Therapy (VMAT) techniques to increase homogeneity of delivered radiation. As a first approach, a dosimetric plan was performed on a computed tomography (CT) scan of a Rando Alderson antropomorfic phantom (head and torso), using a set of six arcs distributed along the phantom. However, a full body anthropomorphic phantom is essential to carry out technique validation and implementation. Our aim is to define the physical and chemical characteristics and the ideal manufacturing procedure of upper and lower limbs to our anthropomorphic phantom, for later validate TBI using VMAT. Materials and Methods: To study the better fit between our phantom and limbs, a CT scan of Rando Alderson anthropomorphic phantom was acquired. CT was performed on GE Healthcare equipment (model Optima CT580 W), with slice thickness of 2.5 mm. This CT was also used to access the electronic density of soft tissue and bone through Hounsfield units (HU) analysis. Results: CT images were analyzed and measures were made for the ideal upper and lower limbs. Upper limbs should be build under the following measures: 43cm length and 7cm diameter (next to the shoulder section). Lower limbs should be build under the following measures: 79cm length and 16.5cm diameter (next to the thigh section). As expected, soft tissue and bone have very different electronic density. This is important to choose and analyze different materials to better represent soft tissue and bone characteristics. The approximate HU values of the soft tissue and for bone shall be 35HU and 250HU, respectively. Conclusion: At the moment, several compounds are being developed based on different types of resins and additives in order to be able to control and mimic the various constituent densities of the tissues. Concurrently, several manufacturing techniques are being explored to make it possible to produce the upper and lower limbs in a simple and non-expensive way, in order to finally carry out a systematic and appropriate study of the total body irradiation. This preliminary study was a good starting point to demonstrate the feasibility of TBI with VMAT.

Keywords: TBI, VMAT, anthropomorphic phantom, tissue equivalent materials

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Authors: Salim Belouettar, Kodjo Attipou

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The thermal wrinkling behavior of thin membranes is investigated. The Fourier double scale series are used to deduce the macroscopic membrane wrinkling equations. The obtained equations account for the global and local wrinkling modes. Numerical examples are conducted to assess the validity of the approach developed. Compared to the finite element full model, the present model needs only few degrees of freedom to recover accurately the bifurcation curves and wrinkling paths. Different parameters such as membrane’s aspect ratio, wave number, pre-stressed membranes are discussed from a numerical point of view and the properties of the wrinkles (critical load, wavelength, size and location) are presented.

Keywords: wrinkling, thermal stresses, Fourier series, thin membranes

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Authors: Noureddine Mahmoudi

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The use of natural fibers in the development of composite materials is a sector in full expansion. These fibers were used for their low cost, their availability and their renewable character. The fibers of the palm (palm tree) were used as reinforcement in polypropylene (PP). The date palm fibers have some potential because of their ecological and economic interest. Both unmodified and compatibilized fibers are used. Compatibilization was carried out with the use of maleic anhydride copolymers. The morphology and mechanical properties were characterized by electron microscopy scanning (SEM) and tensile tests. The influence of fiber content on mechanical properties of composite PP / date palm has been evaluated and demonstrated, that the maximum stress and elongation decreases with increasing fiber volume rate. On the other hand, an increase of the tensile modulus has been noticed, but after the fibers improvement, the maximum stress increases significantly up to 25% weight.

Keywords: plant fiber, palm, SEM, compatibilizer

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Authors: Raj Kumar Rajak, Bharat Mishra

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Bio-batteries represent an entirely new long-term, reasonable, reachable and ecofriendly approach to produce sustainable energy. In the present experimental work, we have studied the effect of generation of power by bio-battery using different electrode pairs. The tests show that it is possible to generate electricity using cow dung as an electrolyte. C-Mg electrode pair shows maximum voltage and SCC (Short Circuit Current) while C-Zn electrode pair shows less OCV (Open Circuit Voltage) and SCC. We have chosen C-Zn electrodes because Mg electrodes are not economical. By the studies of different electrodes and cow dung, it is found that C-Zn electrode battery is more suitable. This result shows that the bio-batteries have the potency to full fill the need of electricity demand for lower energy equipment.

Keywords: bio-batteries, electricity, cow-dung, electrodes, non-conventional

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Authors: Christian Doppler, Gernot Hirschl, Gerhard Zsiga

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Starting from 2020, an EU-wide CO2-limitation of 95g/km is scheduled for the average of an OEMs passenger car fleet. Considering that, further measures of optimization on the diesel cycle will be necessary in order to reduce fuel consumption and emissions while keeping performance values adequate at the least. The present article deals with charge air cooling (CAC) on the basis of a diesel passenger car model in a 0D/1D-working process calculation environment. The considered engine is a 2.4 litre EURO VI diesel engine with variable geometry turbocharger (VGT) and low-pressure exhaust gas recirculation (LP EGR). The object of study was the impact of charge air cooling on the engine working process at constant boundary conditions which could have been conducted with an available and validated engine model in AVL BOOST. Part load was realized with constant power and NOx-emissions, whereas full load was accomplished with a lambda control in order to obtain maximum engine performance. The informative results were used to implement a simulation model in Matlab/Simulink which is further integrated into a full vehicle simulation environment via coupling with ICOS (Independent Co-Simulation Platform). Next, the dynamic engine behavior was validated and modified with load steps taken from the engine test bed. Due to the modular setup in the Co-Simulation, different CAC-models have been simulated quickly with their different influences on the working process. In doing so, a new cooler variation isn’t needed to be reproduced and implemented into the primary simulation model environment, but is implemented quickly and easily as an independent component into the simulation entity. By means of the association of the engine model, longitudinal dynamics vehicle model and different CAC models (air/air & water/air variants) in both steady state and transient operational modes, statements are gained regarding fuel consumption, NOx-emissions and power behavior. The fact that there is no more need of a complex engine model is very advantageous for the overall simulation volume. Beside of the simulation with the mentioned demonstrator engine, there have also been conducted several experimental investigations on the engine test bench. Here the comparison of a standard CAC with an intake-manifold-integrated CAC was executed in particular. Simulative as well as experimental tests showed benefits for the water/air CAC variant (on test bed especially the intake manifold integrated variant). The benefits are illustrated by a reduced pressure loss and a gain in air efficiency and CAC efficiency, those who all lead to minimized emission and fuel consumption for stationary and transient operation.

Keywords: air/water-charge air cooler, co-simulation, diesel working process, EURO VI fuel consumption

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Authors: Gabriel Fernando Talero Rojas, Vladimir Silva Leal, Camilo Bayona-Roa, Juan Pava, Mauricio Lopez Gomez

Abstract:

The substitution of conventional aviation fuels with biomass-derived alternative fuels is an emerging field of study in the aviation transport, mainly due to its energy consumption, the contribution to the global Greenhouse Gas - GHG emissions and the fossil fuel price fluctuations. Nevertheless, several challenges remain as the biofuel production cost and its degradative effect over the fuel systems that alter the operating safety. Moreover, experimentation on full-scale aeronautic turbines are expensive and complex, leading to most of the research to the testing of small-size turbojets with a major absence of information regarding the effects in the energy performance and the emissions. The main purpose of the current study is to present the results of experimentation in a full-scale military turbojet engine J69-T-25A (presented in Fig. 1) with 640 kW of power rating and using blends of Jet A1 with oil palm biodiesel. The main findings are related to the thrust specific fuel consumption – TSFC, the engine global efficiency – η, the air/fuel ratio – AFR and the volume fractions of O2, CO2, CO, and HC. Two fuels are used in the present study: a commercial Jet A1 and a Colombian palm oil biodiesel. The experimental plan is conducted using the biodiesel volume contents - w_BD from 0 % (B0) to 50 % (B50). The engine operating regimes are set to Idle, Cruise, and Take-off conditions. The turbojet engine J69 is used by the Colombian Air Force and it is installed in a testing bench with the instrumentation that corresponds to the technical manual of the engine. The increment of w_BD from 0 % to 50 % reduces the η near 3,3 % and the thrust force in a 26,6 % at Idle regime. These variations are related to the reduction of the 〖HHV〗_ad of the fuel blend. The evolved CO and HC tend to be reduced in all the operating conditions when increasing w_BD. Furthermore, a reduction of the atomization angle is presented in Fig. 2, indicating a poor atomization in the fuel nozzle injectors when using a higher biodiesel content as the viscosity of fuel blend increases. An evolution of cloudiness is also observed during the shutdown procedure as presented in Fig. 3a, particularly after 20 % of biodiesel content in the fuel blend. This promotes the contamination of some components of the combustion chamber of the J69 engine with soot and unburned matter (Fig. 3). Thus, the substitution of biodiesel content above 20 % is not recommended in order to avoid a significant decrease of η and the thrust force. A more detail examination of the mechanical wearing of the main components of the engine is advised in further studies.

Keywords: aviation, air to fuel ratio, biodiesel, energy performance, fuel atomization, gas turbine

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Authors: A. A. Selaimia, H. Bensouilah, M. A. Yallese, I. Meddour, S. Belhadi, T. Mabrouki

Abstract:

The objective of this work is to model the output responses namely; surface roughness (Ra), cutting force (Fc), during the face milling of the austenitic stainless steel X2CrNi18-9 with coated carbide tools (GC4040). For raison, response surface methodology (RMS) is used to determine the influence of each technological parameter. A full factorial design (L27) is chosen for the experiments, and the ANOVA is used in order to evaluate the influence of the technological cutting parameters namely; cutting speed (Vc), feed per tooth, and depth of cut (ap) on the out-put responses. The results reveal that (Ra) is mostly influenced by (fz) and (Fc) is found considerably affected by (ap).

Keywords: austenitic stainless steel, ANOVA, coated carbide, response surface methodology (RSM)

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Authors: Raphael Zanella

Abstract:

This works deals with the finite element approximation of axisymmetric problems. The weak formulation of the heat equation under the axisymmetry assumption is established for continuous finite elements. The weak formulation is implemented in a C++ solver with implicit march-in-time. The code is verified by space and time convergence tests using a manufactured solution. The solving of an example problem with an axisymmetric formulation is compared to that with a full-3D formulation. Both formulations lead to the same result, but the code based on the axisymmetric formulation is much faster due to the lower number of degrees of freedom. This confirms the correctness of our approach and the interest in using an axisymmetric formulation when it is possible.

Keywords: axisymmetric problem, continuous finite elements, heat equation, weak formulation

Procedia PDF Downloads 204