Search results for: computerized dynamic assessment

Authors: Rod Davis, Sara Saminfar

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Earthquakes can induce dynamic earth pressures on retaining walls, which are in addition to the static earth pressures. This raises questions about how to effectively combine the seismic lateral earth pressure with other loads on buildings, including static lateral earth pressure. When basement walls retain soil with differing exterior grades on opposite sides, the seismic increment of active earth pressure should be considered. Additionally, buildings situated on sloped sites with stepped retention may experience unique dynamic effects due to soil-structure interactions, potentially amplifying the lateral pressures exerted on the retaining walls and influencing the building's response during seismic events. To account for the dynamic effects of the retained soil on the building's responses, it is essential to interconnect the building structure with the surrounding soil to facilitate their interaction as the embedded structure and the surrounding soil move together during an earthquake. Consequently, a finite element model of the building is developed, with the rigid retaining walls and restrained to the floor diaphragms. This paper aims to explore the dynamic effects of retained soil on the lateral stability of buildings and the sensitivity of the building's responses to differences in the retained heights on opposite sides of the building basement. Furthermore, the results are compared with those from a sloped site to evaluate the impact of stepped retention on dynamic soil pressure. These findings will help establish a minimum threshold for differences in retained heights on opposite sides of a building that necessitates the inclusion of dynamic soil pressure in the building's lateral stability analysis.

Keywords: dynamic earth pressures, soil-structure interaction, stepped retention, building retention

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Authors: Ahmed R. Z. Baghdadi,  Mona H. Gamal Eldein

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Background: With the perceived pain and poor function experienced following knee arthroplasty, patients usually feel unsatisfied. Yet, a controversy still persists on the appropriate operative technique that doesn’t affect proprioception much. Purpose: This study compared the effects of Cruciate Retaining (CR) and Posterior Stabilized (PS) total knee arthroplasty (TKA on dynamic balance, pain and functional performance following rehabilitation. Methods: Thirty patients with CRTKA (group I), thirty with PSTKA (group II) and fifteen indicated for arthroplasty but weren’t operated on yet (group III) participated in the study. The mean age was 54.53±3.44, 55.13±3.48 and 55.33±2.32 years and BMI 35.7±3.03, 35.7±1.99 and 35.73±1.03 kg/m2 for group I, II, and III respectively. The Berg Balance Scale (BBS), WOMAC pain subscale and Timed-Up-and-Go (TUG) and Stair-Climbing (SC) tests were used for assessment. Assessments were conducted four weeks pre- and post-operatively, three, six and twelve months post-operatively with the control group being assessed at the same time intervals. The post-operative rehabilitation involved hospitalization (1st week), home-based (2nd-4th weeks), and outpatient clinic (5th-12th weeks) programs, follow-up to all groups for twelve months. Results: The Mixed design MANOVA revealed that group I had significantly lower pain scores and SC time compared with group II three, six and twelve months post-operatively. Moreover, the BBS scores increased significantly and the pain scores and TUG and SC time decreased significantly six months post-operatively compared with four weeks pre- and post-operatively and three months post-operatively in group I and II with the opposite being true four weeks post-operatively. But no significant differences in BBS scores, pain scores and TUG and SC time between six and twelve months post-operatively in group I and II. Interpretation/Conclusion: CRTKA is preferable to PSTKA, possibly due to the preserved human proprioceptors in the un-excised PCL.

Keywords: dynamic balance, functional performance, knee arthroplasty, long-term

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Authors: Kibreab Alene Fenite

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The purpose of this study is to investigate the implementation and challenges of different assessment methods for physical education class in some selected preparatory schools of kirkos sub city. The participants in this study are teachers, students, department heads and school principals from 4 selected schools. Of the total 8 schools offering in kirkos sub city 4 schools (Dandi Boru, Abiyot Kirse, Assay, and Adey Ababa) are selected by using simple random sampling techniques and from these schools all (100%) of teachers, 100% of department heads and school principals are taken as a sample as their number is manageable. From the total 2520 students, 252 (10%) of students are selected using simple random sampling. Accordingly, 13 teachers, 252 students, 4 department heads and 4 school principals are taken as a sample from the 4 selected schools purposefully. As a method of data gathering tools; questionnaire and interview are employed. To analyze the collected data, both quantitative and qualitative methods are used. The result of the study revealed that assessment in physical education does not implement properly: lack of sufficient materials, inadequate time allotment, large class size, and lack of collaboration and working together of teachers towards assessing the performance of students, absence of guidelines to assess the physical education subject, no different assessment method that is implementing on students with disabilities in line with their special need are found as major challenges in implementing the current assessment method of physical education. To overcome these problems the following recommendations have been forwarded. These are: the necessary facilities and equipment should be available; In order to make reliable, accurate, objective and relevant assessment, teachers of physical education should be familiarized with different assessment techniques; Physical education assessment guidelines should be prepared, and guidelines should include different types of assessment methods; qualified teachers should be employed, and different teaching room must be build.

Keywords: assessment, challenges, equipment, guidelines, implementation, performance

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Authors: S. Houcine Habib, B. Elkhalil Hachi, Mohamed Guesmi, Mohamed Haboussi

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In this paper, dynamic fracture behaviors of cracked orthotropic structure are modeled using extended finite element method (X-FEM). In this approach, the finite element method model is first created and then enriched by special orthotropic crack tip enrichments and Heaviside functions in the framework of partition of unity. The mixed mode stress intensity factor (SIF) is computed using the interaction integral technique based on J-integral in order to predict cracking behavior of the structure. The developments of these procedures are programmed and introduced in a self-software platform code. To assess the accuracy of the developed code, results obtained by the proposed method are compared with those of literature.

Keywords: X-FEM, composites, stress intensity factor, crack, dynamic orthotropic behavior

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Authors: Daleesha M. Viswanathan, Sumam Mary Idicula

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Dynamic hand gestures are an intrinsic component in sign language communication. Extracting spatial temporal features of the hand gesture trajectory plays an important role in a dynamic gesture recognition system. Finding a discrete feature descriptor for the motion trajectory based on the orientation feature is the main concern of this paper. Kalman filter algorithm and Hidden Markov Models (HMM) models are incorporated with this recognition system for hand trajectory tracking and for spatial temporal classification, respectively.

Keywords: orientation features, discrete feature vector, HMM., Indian sign language

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Authors: Fstemeh Rais Esmaili, Ehsan Ranjbar

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Pedestrian streets as one type of urban public spaces have an important role in improving the quality of urban life. In Iran, planning and designing of pedestrian streets is in its primary steps. In spite of starting this approach in Iran, and designing several pedestrian streets, there are still not organized studies about quality assessment of pedestrian streets. As a result, the strength and weakness points of the initial experiences have not been utilized. This inattention to quality assessment have caused designing pedestrian streets to be limited to just vehicles traffic control and preliminary actions like paving; so that, special potentials of pedestrian streets for creating social, livable and dynamic public spaces have not been used. This article, as an organized study about quality assessment of pedestrian streets in Iran, tries to reach two main goals: first, introducing a framework for quality assessment of pedestrian streets in Iran, and second, creating a context for improving the quality of pedestrian streets especially for further experiences. The main research methods are description and context analyzing. With respect to comparative analysis of ideas about quality, considering international and local case studies and analyzing existing condition of Saf Pedestrian Street, a particular model for quality assessment has been introduced. In this model, main components and assessment criteria have been presented. On the basis of this model, questionnaire and checklist for assessment have been prepared. The questionnaire and interview have been used to assess qualities which are in direct contact with people and the checklist has been used for analyzing visual qualities by authors through observation. Some results of questionnaire and checklist show that 7 of 11 primary components, diversity, flexibility, cleanness, legibility and imaginably, identity, livability, form and physical setting are rated low and very low in quality degree. Three components, efficiency, comfort and distinctiveness, have medium and low quality degree and one component, access, linkage and permeability has high quality degree. Therefore, based on implemented analyzing process, Saf Pedestrian Street needs to be improved and these quality improvement priorities are determined based on presented criteria. Adaption of final results with existing condition illustrates the shortage of services for satisfying user’s needs, inflexibility and impossibility of using spaces in various times, lack of facilities for different climatic conditions, lack of facilities such as drinking fountain, inappropriate designing of existing urban furniture like garbage cans, and creating pollution and unsuitable view, lack of visual attractions, neglecting disabled persons in designing entrances, shortage of benches and their undesirable designing, lack of vegetation, absence of special characters making it different from other streets, preventing people taking part in the space causing lack of affiliation, lack of appropriate elements for leisure time and lack of exhilaration in the space. On the other hand, these results present high access and permeability, high safety, less sound pollution and more relief, comfortable movement along the way due to suitable pavement and economic efficiency, as the strength points of Saf pedestrian street.

Keywords: pedestrian streets, quality assessment, quality criteria, Saf Pedestrian Street

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Authors: Ahmed Guerine, Ali El Hafidi, Bruno Martin, Philippe Leclaire

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In this paper, we propose a method for the dynamic response of multi-storey structures with uncertain-but-bounded parameters. The effectiveness of the proposed method is demonstrated by a numerical example of three-storey structures. This equation is integrated numerically using Newmark’s method. The numerical results are obtained by the proposed method. The simulation accounting the interval analysis method results are compared with a probabilistic approach results. The interval analysis method provides a mean curve that is between an upper and lower bound obtained from the probabilistic approach.

Keywords: multi-storey structure, dynamic response, interval analysis method, random parameters

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Authors: Maryam Azimi, Amin Banitalebi-Dehkordi, Yuanyuan Dong, Mahsa T. Pourazad, Panos Nasiopoulos

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While there exists a wide variety of Low Dynamic Range (LDR) quality metrics, only a limited number of metrics are designed specifically for the High Dynamic Range (HDR) content. With the introduction of HDR video compression standardization effort by international standardization bodies, the need for an efficient video quality metric for HDR applications has become more pronounced. The objective of this study is to compare the performance of the existing full-reference LDR and HDR video quality metrics on HDR content and identify the most effective one for HDR applications. To this end, a new HDR video data set is created, which consists of representative indoor and outdoor video sequences with different brightness, motion levels and different representing types of distortions. The quality of each distorted video in this data set is evaluated both subjectively and objectively. The correlation between the subjective and objective results confirm that VIF quality metric outperforms all to their tested metrics in the presence of the tested types of distortions.

Keywords: HDR, dynamic range, LDR, subjective evaluation, video compression, HEVC, video quality metrics

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Authors: Laurence Craven

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Academic writing is one of the most important class a freshman will take, as it provides the skill needed to formulate an academic essay in any discipline. Written assignments are the most common form of assessment in higher education and thus it is of paramount importance for students to master the skill of academic writing. This presentation aims to give practitioners multiple ways to enhance their academic writing classes using the Blackboard environment, with a view to improving student performance. The presentation will include ways to improve assessment and give corrective feedback. It will also provide ideas on how to increase variety in teaching lessons, assigning homework and on organizing materials.

Keywords: academic writing, assessment, e-learning, technology

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Authors: Mohammad Hadi Jalali, Behrooz Shahriari, Mostafa Ghayour, Saeed Ziaei-Rad, Shahram Yousefi

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Most flexible rotors can be considered as beam-like structures. In many cases, rotors are modeled as one-dimensional bodies, made basically of beam-like shafts with rigid bodies attached to them. This approach is typical of rotor dynamics, both analytical and numerical, and several rotor dynamic codes, based on the finite element method, follow this trend. In this paper, a finite element model based on Timoshenko beam elements is utilized to analyze the lateral dynamic behavior of a certain rotor-bearing system in operating conditions.

Keywords: finite element method, Timoshenko beam elements, operational deflection shape, unbalance response

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Authors: Dragana Gnjatovic

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Assessment is a burning topic in education policy and practice due to measurement-driven neoliberal agendas of quality and standardisation of assessment practice through high stakes standardised testing systems that are now influencing early childhood education. This paper presents a collaborative, arts-informed action research project which places children at the centre of their learning, with assessment as an integral part of play-based learning processes. It aims to challenge traditional approaches to assessment that are often teacher-led and decontextualised from the processes of learning through exploring approaches where children's voices are central, and their creative arts expressions are used to assess learning and development. The theoretical framework draws on Vygotsky's sociocultural theory and Freire's critical pedagogy, which indicate the importance of socially constructed reality where knowledge is the result of collaboration between children and adults. This reality perceives children as competent agents of their own learning processes. An interpretive-constructivist and critical-transformative paradigm underpin collaborative action research in a three to five-year-old setting, where creative methods like storytelling, play, drama, drawing are used to assess children's learning. As data collection and analysis are still in process, this paper will present the methodology and some data vignettes, with the aim of stimulating discussion about innovation in assessment and contribution of the collaborative enquiry in the field of Early Childhood Education and Care.

Keywords: assessment for learning, creative methodologies, collaborative action research, early childhood education and care

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Authors: P. Ravinder Reddy, Chaitanya Vishal Nalli, B. Tulja Lal, Anusha Kankanala

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The chassis frame of an automobile with different sections have been considered for different loads. The orthotropic materials are selected to get the stability by varying fiber angle, fiber thickness, laminates, fiber properties, matrix properties and elastic ratios. The geometric model of chassis frame is carried out with parametric modelling approach. The analysis of chassis frame is carried out with ANSYS FEA software. The static and dynamic analysis of chassis frame is carried out by varying geometric parameters, orthotropic properties, materials and various sections. The static and dynamic response is discussed in detail in different sections.

Keywords: chassis frame, dynamic response, geometric model, orthotropic materials

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Authors: Khawar Naeem, Adel Elomri, Adel Zghibi

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Contamination leakage from municipal solid waste (MSW) landfills is a serious environmental challenge that poses a threat to interconnected ecosystems. It not only contaminates the soil of the saturated zone, but it also percolates down the earth and contaminates the groundwater (GW). In this concise literature review, an effort is made to understand the environmental hazards posed by this contamination to the soil and groundwater, the type of contamination, and possible solutions proposed in the literature. In the study’s second phase, the MSW management practices are explored as the landfill site dump rate and type of MSW into the landfill site directly depend on the MSW management strategies. Case studies from multiple developed and underdeveloped countries are presented, and the complex MSW management system is investigated from an operational perspective to minimize the contamination of GW. One of the significant tools used in the literature was found to be Systems Dynamic Modeling (SDM), which is a simulation-based approach to study the stakeholder’s approach. By employing the SDM approach, the risk of GW contamination can be reduced by devising effective MSW management policies, ultimately resulting in water resource sustainability and regional sustainable development.

Keywords: groundwater contamination, environmental risk, municipal solid waste management, system dynamic modeling, water resource sustainability, sustainable development

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Authors: Mohamed Moustafa Mahmoud Sedky

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In line start permanent magnet synchronous motor, eccentricity is a common fault that can make it necessary to remove the motor from the production line. However, because the motor may be inaccessible, diagnosing the fault is not easy. This paper presents an FEM that identifies different models, static eccentricity, dynamic eccentricity, and mixed eccentricity, at no load and full load. The method overcomes the difficulty of applying FEMs to transient behavior. It simulates motor speed, torque and flux density distribution along the air gap for SE, DE, and ME. This paper represents the various effects of different eccentricities types on the transient performance.

Keywords: line start permanent magnet, synchronous machine, static eccentricity, dynamic eccentricity, mixed eccentricity

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Authors: B. V. Santos, M. T. M. Carvalho, J. H. S. Rêgo

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The article presents a literature review on recent advances related to studies of the environmental impact of road pavements, with reference to the concepts of Life Cycle Assessment (LCA). An introduction with the main motivations for the development of the research is presented, with a current overview of the Brazilian transport infrastructure and the projections for the road mode for the coming years, and the possibility of using the referred methodology by the road sector in Brazil. The article explores the origin of LCA in road pavements and the details linked to its implementation from the perspective of the four main phases of the study (goal and scope definition, inventory analysis, impact assessment, and interpretation). Finally, the main advances and deficiencies observed in the selected studies are gathered, with the proposition of research fields that can be explored in future national or international studies of LCA of road pavements.

Keywords: Brazil, life cycle assessment, road pavements, sustainable

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Authors: Daniel A. Montoya, Marta L. Tostes

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This investigation aims at analyzing and determining the relation between two very important variables in the human resource management: The organizational climate and the performance assessment. This study aims at contributing with knowledge in the search of the relation between the mentioned variables because the literature still does not provide solid evidence to this respect and the cases revised are incipient to reach conclusions enabling a typology about this relation.To this regard, a correlational and cross-sectional perspective was adopted in which quantitative and qualitative techniques were chosen with the total of the workers of the tourist service company PTS Peru. In order to measure the organizational climate, the OCQ (Organization Climate Questionnaire) from was used; it has 50 items and measures 9 dimensions of the Organizational Climate. Also, to assess performance, a questionnaire with 21 items and 6 dimensions was designed. As a means of assessment, a focus group was prepared and was applied to a worker in every area of the company. Additionally, interviews to human resources experts were conducted. The results of the investigation show a clear relation between the organizational climate and the personnel performance assessment as well as a relation between the nine dimensions of the organizational climate and the work performance in general and with some of its dimensions.

Keywords: job performance, job satisfaction, organization climate, performance assessment

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Authors: Khoa K. Doan

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Assessment plays an essential role in teaching and learning English as it aims to measure the learning outcomes. Designing appropriate test types and procedures for four skills, especially productive skills, is a very challenging task for teachers of English. The assessment scheme is supposed to provide precise measures and fair opportunities for students to demonstrate what they can do with their language skills. This involves content domains, measurement techniques, administrative feasibility, target populations, and potential sources of testing bias. Based on these elements, a review of end-of-term speaking tests for English-majored students at Ho Chi Minh City Open University (Viet Nam) was undertaken for the purpose of analyzing the strengths and limitations of the testing tool for the speaking assessment. It helped to identify what could be done to facilitate the process of teaching and learning in that context.

Keywords: assessment, oral tests, speaking, testing

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Authors: Mohammad Reza Ameri, Ali Massumi, Mohammad Haghbin

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Non-linear static analysis, commonly referred to as pushover analysis, is a powerful tool for assessing the seismic response of structures. A suitable lateral load pattern for pushover analysis can bring the results of this simple, quick and low-cost analysis close to the realistic results of nonlinear dynamic analyses. In this research, four samples of 10- and 15 story (two- and four-bay) reinforced concrete frames were studied. The lateral load distribution patterns recommended in FEMA 273/356 guidelines were applied to the sample models in order to perform pushover analyses. The results were then compared to the results obtained from several nonlinear incremental dynamic analyses for a range of earthquakes. Finally, a lateral load distribution pattern was proposed for pushover analysis of medium-rise reinforced concrete buildings based on the results of nonlinear static and dynamic analyses.

Keywords: lateral load pattern, nonlinear static analysis, incremental dynamic analysis, medium-rise reinforced concrete frames, performance based design

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Authors: Ajish Sreedharan

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Security in transmission and storage of digital images has its importance in today’s image communications and confidential video conferencing. Due to the increasing use of images in industrial process, it is essential to protect the confidential image data from unauthorized access. Advanced Encryption Standard (AES) is a well known block cipher that has several advantages in data encryption. However, it is not suitable for real-time applications. This paper presents modifications to the Advanced Encryption Standard to reflect a high level security and better image encryption. The modifications are done by adjusting the ShiftRow Transformation and using On Dynamic chaotic S-BOX. In AES the Substitute bytes, Shift row and Mix columns by themselves would provide no security because they do not use the key. In Dynamic chaotic S-BOX Based AES the Substitute bytes provide security because the S-Box is constructed from the key. Experimental results verify and prove that the proposed modification to image cryptosystem is highly secure from the cryptographic viewpoint. The results also prove that with a comparison to original AES encryption algorithm the modified algorithm gives better encryption results in terms of security against statistical attacks.

Keywords: advanced encryption standard (AES), on dynamic chaotic S-BOX, image encryption, security analysis, ShiftRow transformation

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Authors: Amizawati Mohd Amir, Ruhanita Maelah, Zaidi Mohd Noor

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As part of the Malaysia Higher Institutions' Strategic Plan in promoting high-quality research and education, the Ministry of Higher Education has introduced various instrument to assess the universities performance. The aims are that university will produce more commercially-oriented research and continue to contribute in producing professional workforce for domestic and foreign needs. Yet the spirit of the success lies in the commitment of university particularly the academic staff to translate the vision into reality. For that reason, the element of fairness and justice in assessing individual academic staff performance is crucial to promote directly linked between university and individual work goals. Focusing on public research universities (RUs) in Malaysia, this study observes at the issue through the practice of university contemporary performance measurement system. Accordingly management control theory has conceptualized that contemporary performance measurement consisting of three dimension namely strategic, comprehensive and dynamic building upon equity theory, the relationships between contemporary performance measurement system and organizational justice and in turn the effect on academic staff work performance are tested based on online survey data administered on 365 academic staff from public RUs, which were analyzed using statistics analysis SPSS and Equation Structure Modeling. The findings validated the presence of strategic, comprehensive and dynamic in the contemporary performance measurement system. The empirical evidence also indicated that contemporary performance measure and procedural justice are significantly associated with work performance but not for distributive justice. Furthermore, procedural justice does mediate the relationship between contemporary performance measurement and academic staff work performance. Evidently, this study provides evidence on the importance of perceptions of justice towards influencing academic staff work performance. This finding may be a fruitful input in the setting up academic staff performance assessment policy.

Keywords: comprehensive, dynamic, distributive justice, contemporary performance measurement system, strategic, procedure justice, work performance

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Authors: S. S. Adamu, H. S. Muhammad, D. S. Shuaibu

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Poor power quality in electrical power systems can lead to medical equipment at healthcare centres to malfunction and present wrong medical diagnosis. Equipment such as X-rays, computerized axial tomography, etc. can pollute the system due to their high level of harmonics production, which may cause a number of undesirable effects like heating, equipment damages and electromagnetic interferences. The conventional approach of mitigation uses passive inductor/capacitor (LC) filters, which has some drawbacks such as, large sizes, resonance problems and fixed compensation behaviours. The current trends of solutions generally employ active power filters using suitable control algorithms. This work focuses on assessing the level of Total Harmonic Distortion (THD) on medical facilities and various ways of mitigation, using radiology unit of an existing hospital as a case study. The measurement of the harmonics is conducted with a power quality analyzer at the point of common coupling (PCC). The levels of measured THD are found to be higher than the IEEE 519-1992 standard limits. The system is then modelled as a harmonic current source using MATLAB/SIMULINK. To mitigate the unwanted harmonic currents a shunt active filter is developed using synchronous detection algorithm to extract the fundamental component of the source currents. Fuzzy logic controller is then developed to control the filter. The THD without the active power filter are validated using the measured values. The THD with the developed filter show that the harmonics are now within the recommended limits.

Keywords: power quality, total harmonics distortion, shunt active filters, fuzzy logic

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Authors: Nurullah Buker, Ezgi Karagoz, Yesim Salik Sengul, Sevay Alsen Guney, Gokhan Yoyler, Aylin Ozbek

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Attention Deficit Hyperactivity Disorder (ADHD) is one of the most common neurodevelopmental disorders with heterogeneous clinical features such as inattention, hyperactivity, and impulsivity. Many different types of exercise interventions were employed for children with ADHD. However, previous studies have usually examined the effects of non-specific exercise programs or short-term effects of exercise. The aim of this study is to investigate the effect of the Neurocognitive Exercise Program (NEP), which is a structured exercise program derived from Life Kinetik, and a relatively new for children with ADHD, on symptoms, attention, and dynamic balance in medication-naïve children with ADHD. Fourteen medication-naive children (7-12 years) with ADHD were included in the intervention group. NEP was performed once a week for ten weeks. The intervention group also performed a structured home exercise program for another six days, for ten weeks. The children in the intervention group were assessed at baseline, in the third month, in the sixth month, and in the twelfth month regarding ADHD-related symptoms, attention, and dynamic balance. Fifteen age-matched typically developing children were assessed once for establishing normative values. Hyperactivity-Impulsivity score and dynamic balance were found to improve after NEP in the ADHD group in the 3rd month (p<0.05). In addition, these results were similar for both groups after NEP and at the end of the 12th month (p>0.05). The NEP may provide beneficial effects on hyperactivity-impulsivity, oppositional defiant, and dynamic balance in children with ADHD, and the improvements may be maintained in the long term.

Keywords: ADHD, attention problems, dynamic balance, neurocognitive exercise

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Authors: Jui-Pui Hung, Yu-Sheng Lai, Tzuo-Liang Luo, Kung-Da Wu, Yun-Ji Zhan

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This study presented the investigation of the influence of the tool holder interface stiffness on the dynamic characteristics of a spindle tool system. The interface stiffness was produced by drawbar force on the tool holder, which tends to affect the spindle dynamics. In order to assess the influence of interface stiffness on the vibration characteristic of spindle unit, we first created a three dimensional finite element model of a high speed spindle system integrated with tool holder. The key point for the creation of FEM model is the modeling of the rolling interface within the angular contact bearings and the tool holder interface. The former can be simulated by a introducing a series of spring elements between inner and outer rings. The contact stiffness was calculated according to Hertz contact theory and the preload applied on the bearings. The interface stiffness of the tool holder was identified through the experimental measurement and finite element modal analysis. Current results show that the dynamic stiffness was greatly influenced by the tool holder system. In addition, variations of modal damping, static stiffness and dynamic stiffness of the spindle tool system were greatly determined by the interface stiffness of the tool holder which was in turn dependent on the draw bar force applied on the tool holder. Overall, this study demonstrates that identification of the interface characteristics of spindle tool holder is of very importance for the refinement of the spindle tooling system to achieve the optimum machining performance.

Keywords: dynamic stiffness, spindle-tool holder, interface stiffness, drawbar force

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Authors: Fabrizio Iezzi, Claudio Valente

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The viscous damping in dynamic systems can be proportional or non-proportional. In the first case, the mode shapes are real whereas in the second case they are complex. From an engineering point of view, the complexity of the mode shapes is important in order to quantify the non-proportional damping. Different indices exist to provide estimates of the modal complexity. These indices are or not zero, depending whether the mode shapes are not or are complex. The modal density problem arises in the experimental identification when the dynamic systems have close modal frequencies. Depending on the entity of this closeness, the mode shapes can hold fictitious imaginary quantities that affect the values of the modal complexity indices. The results are the failing in the identification of the real or complex mode shapes and then of the proportional or non-proportional damping. The paper aims to show the influence of the modal density on the values of these indices in case of both proportional and non-proportional damping. Theoretical and pseudo-experimental solutions are compared to analyze the problem according to an appropriate mechanical system.

Keywords: complex mode shapes, dynamic systems identification, modal density, non-proportional damping

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Authors: A. Bogdanovic, M. Vitanova, J. Bojadjieva, Z. Rakicevic, V. Sesov, K. Edip, N. Naumovski, F. Manojlovski, A.Popovska, A. Shoklarovski, T. Kitanovski, D. Ivanovski, I. Markovski, D. Filipovski

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The conditions of existing structures change in the course of time and can hardly be characterized particularly if a bridge has long been in function and there is no design documentation related to it. To define the real conditions of a structure, detailed static and dynamic analysis of the structure has to be carried out and its modal parameters have to be defined accurately. Modal analysis enables a quite accurate identification of the natural frequencies and mode shapes. Presented in this paper are the results from the performed detailed analyses of a steel truss bridge that has been in use for more than 7 decades by the military services of R.N. Macedonia and for which there is no documentation at all. Static and dynamic investigations and ambient vibration measurements were performed. The acquired data were used to identify the mode shapes that were used for comparison with the numerical model. Dynamic tests were performed to define the bridge behaviour and the damping index. Finally, based on all the conducted detailed analyses and investigations, conclusions on the conditions of the bridge structure were drawn.

Keywords: ambient vibrations, dynamic identification, in-situ measurement, steel truss bridge

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Authors: Norzaliza Md. Nor, Sh-Hussain Salleh, Mahyar Hamedi, Hadrina Hussain, Wahab Abdul Rahman

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Motivational factor is mainly the students’ desire to involve in learning process. However, it also depends on the goal towards their involvement or non-involvement in academic activity. Even though, the students’ motivation might be in the same level, but the basis of their motivation may differ. In this study, it focuses on the intrinsic motivational factor which student enjoy learning or feeling of accomplishment the activity or study for its own sake. The intrinsic motivational factor of students in learning mathematics and science has found as difficult to be achieved because it depends on students’ interest. In the Program for International Student Assessment (PISA) for mathematics and science, Malaysia is ranked as third lowest. The main problem in Malaysian educational system, students tend to have extrinsic motivation which they have to score in exam in order to achieve a good result and enrolled as university students. The use of electroencephalogram (EEG) signals has found to be scarce especially to identify the students’ intrinsic motivational factor in learning science and mathematics. In this research study, we are identifying the correlation between precursor emotion and its dynamic emotion to verify the intrinsic motivational factor of students in learning mathematics and science. The 2-D Affective Space Model (ASM) was used in this research in order to identify the relationship of precursor emotion and its dynamic emotion based on the four basic emotions, happy, calm, fear and sad. These four basic emotions are required to be used as reference stimuli. Then, in order to capture the brain waves, EEG device was used, while Mel Frequency Cepstral Coefficient (MFCC) was adopted to be used for extracting the features before it will be feed to Multilayer Perceptron (MLP) to classify the valence and arousal axes for the ASM. The results show that the precursor emotion had an influence the dynamic emotions and it identifies that most students have no interest in mathematics and science according to the negative emotion (sad and fear) appear in the EEG signals. We hope that these results can help us further relate the behavior and intrinsic motivational factor of students towards learning of mathematics and science.

Keywords: EEG, MLP, MFCC, intrinsic motivational factor

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Authors: Priti Saha, Biswajit Paul

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Rapid urbanization and industrialization has increased the pollution load in surface water bodies. However, these water bodies are major source of water for drinking, irrigation, industrial activities and fishery. Therefore, water quality assessment is paramount importance to evaluate its suitability for all these purposes. This study focus to evaluate the surface water quality of an industrial city in eastern India through integrating interdisciplinary techniques. The multi-purpose Water Quality Index (WQI) assess the suitability for drinking, irrigation as well as fishery of forty-eight sampling locations, where 8.33% have excellent water quality (WQI:0-25) for fishery and 10.42%, 20.83% and 45.83% have good quality (WQI:25-50), which represents its suitability for drinking irrigation and fishery respectively. However, the industrial water quality was assessed through Ryznar Stability Index (LSI), which affirmed that only 6.25% of sampling locations have neither corrosive nor scale forming properties (RSI: 6.2-6.8). Integration of these statistical analysis with geographical information system (GIS) helps in spatial assessment. It identifies of the regions where the water quality is suitable for its use in drinking, irrigation, fishery as well as industrial activities. This research demonstrates the effectiveness of statistical and GIS techniques for water quality assessment.

Keywords: surface water, water quality assessment, water quality index, spatial assessment

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Authors: Muhammad Rehan Usman, Muhammad Arslan Usman, Soo Young Shin

Abstract:

The new era of digital communication has brought up many challenges that network operators need to overcome. The high demand of mobile data rates require improved networks, which is a challenge for the operators in terms of maintaining the quality of experience (QoE) for their consumers. In live video transmission, there is a sheer need for live surveillance of the videos in order to maintain the quality of the network. For this purpose objective algorithms are employed to monitor the quality of the videos that are transmitted over a network. In order to test these objective algorithms, subjective quality assessment of the streamed videos is required, as the human eye is the best source of perceptual assessment. In this paper we have conducted subjective evaluation of videos with varying spatial and temporal impairments. These videos were impaired with frame freezing distortions so that the impact of frame freezing on the quality of experience could be studied. We present subjective Mean Opinion Score (MOS) for these videos that can be used for fine tuning the objective algorithms for video quality assessment.

Keywords: frame freezing, mean opinion score, objective assessment, subjective evaluation

Procedia PDF Downloads 494

Authors: M. Cangi, T. Dolar, C. Ersoy, Y. E. Aydogdu, A. I. Aydeniz, A. Mugan

Abstract:

The drum is one of the critical parts in a washing machine in which the clothes are washed and spin by the rotational movement. It is activated by the drum shaft which is attached to an electric motor and subjected to dynamic loading. Being one of the critical components, failures of the drum require costly repairs of dynamic components. In this study, tolerance bands between the drum shaft and its two bearings were examined to develop a relationship between the fatigue life of the shaft and the interaction tolerances. Optimization of tolerance bands was completed in consideration of the fatigue life of the shaft as the cost function. The following methodology is followed: multibody dynamic model of a washing machine was constructed and used to calculate dynamic loading on the components. Then, these forces were used in finite element analyses to calculate the stress field in critical components which was used for fatigue life predictions. The factors affecting the fatigue life were examined to find optimum tolerance grade for a given test condition. Numerical results were verified by experimental observations.

Keywords: fatigue life, finite element analysis, tolerance analysis, optimization

Procedia PDF Downloads 157

Authors: Sharaf S. Omar

Abstract:

In the current study, level and prevalence of deoxynivalenol (DON), aflatoxin B1 AFB1), zearalenone (ZEN), and ochratoxin A (OTA) in fried poultry eggs in Jordan was investigated. Poultry egg samples (n = 250) were collected. The level of DON, AFB1, ZEN and OTA in the white and yolk of poultry eggs was measured using LC-MS-MS. The health risk assessment was calculated using Margin of Exposures (MOEs) for AFB1 and OTA and hazard index (HI) for ZEN and DON. The highest prevalence in yolk and white of eggs was related to ZEN (96.56%) and OTA (97.44%), respectively. Also, the highest level in white and yolk was related to DON (1.07µg/kg) and DON (1.65 µg/kg), respectively. Level of DON in the yolk of eggs was significantly higher than white of eggs (P-value < 0.05). Risk assessment indicated that exposed population are at high risk of AFB1 (MOEs < 10,000) in fried poultry eggs.

Keywords: mycotoxins 2, aflatoxin b1, risk assessment, poultry egg

Procedia PDF Downloads 119