Major Design Factors Research Articles

Optimization of a Two-stage Bevel Helical Gearbox using Multiple Objectives to Increase Efficiency and Reduce Gearbox Bottom Area

This study aims to look at multi-target optimization of two-stage bevel helical gearboxes to determine the best major design factors for reducing gearbox bottom area (GBA) and increasing gearbox efficiency (GE). Grey relation analysis (GRA) and the Taguchi technique were used to address the problem in two steps. Prioritizing the closure of the variable level gap, the single-objective optimization problem was addressed, followed by the multi-objective optimization problem, which identified the ideal primary design variables. Additionally, the first-stage gear ratio, allowable contact stresses (ACS), and first and second-stage coefficients of wheel face width (CWFW) were calculated. The outcomes of the study were used to determine the best values for five essential design features of a two-stage bevel helical gearbox (BHG).

Measurements of bulk and contact thermal resistances of PEMFC gas diffusion and microporous layers

The thermal conductivity and thermal contact resistance of gas diffusion layer (GDL) and microporous layer (MPL) are key parameters that affect the performance of proton exchange membrane fuel cells. Conflicting results were reported in previous studies, including the effect of PTFE (Polytetrafluoroethylene) on the GDL effective thermal conductivity, and the magnitude of the thermal contact resistance between the GDL substrate and the MPL coating. In view of this, the two-thickness method is used to measure the thermal conductivity and the thermal contact resistance of a Toray GDL with a MPL coating. The results show that when the loading pressure is increased from 0.25 MPa to 2 MPa, the effective thermal conductivity of the GDL increases from 1.22 W m−1 K−1 to 1.81 W m−1 K−1, while the effective thermal conductivity of the MPL coating remains unchanged at 0.5 W m−1 K−1. Treatment with 20 wt% PTFE reduces the effective thermal conductivity of the GDL by 25%. The thermal contact resistance between the GDL substrate and the MPL coating accounts for only 6.35% of the total thermal resistance of the GDL-MPL components, indicating that this thermal contact resistance is not a major factor in the PEMFC design.

Design and Testing of a Superelastic Nitinol Tissue Attachment Mechanism for Long-Term Gastrointestinal Device Retention

AbstractIngestible devices have become a popular means for diagnosing and treating the gastrointestinal (GI) tract due to their noninvasive nature. However, their residency period in the GI tract is limited by the transit time through it. In previous work, we designed a tissue attachment mechanism (TAM) inspired by parasitic worms' attachment methods, which were tested for implanting biosensors or drug delivery payloads to the small intestine with a swallowable capsule robot. In that work, the attachment success rate was 91.7%, and the average attachment duration of the TAM was 32.2 h after factorial optimization of major design factors. This work develops a novel nitinol TAM (NTAM) for improving the attachment duration using the shape-changing properties of nitinol. The attachment strength of the NTAM to the intestinal tissue was assessed both ex vivo and in vivo. The attachment duration of the NTAMs in live porcine models was evaluated from radiographic images, and histological analysis of the attachment location of an NTAM was performed after euthanasia. The NTAM was 100% successful in an attachment strength study and achieved a maximum attachment duration of 13 days, while the average attachment duration was 85.63 ± 77.83 h. Histological analysis did not report any permanent damage to the tissue. This work shows a 2.7-fold improvement in attachment duration over the previous design. This work has demonstrated a method of prolonged attachment to the intestinal wall through a swallowable device, which can be used for long-term drug delivery or biosensing.

Analysis of Factors Affecting Consumer Interest In Urban Are-as In Shopping For Daily Necessities Online During The Covid-19 Pandemic

Online Shopping is the act of buying products and services through an online store or e-commerce. The culture of online shopping in Indonesia began to develop around the 2000s with the introduction of the internet. One of the benefits obtained by online shopping is that it makes shopping easier and more practical. Buyers do not need to spend time and spend on a trip to a physical store. It has also created a change in one's behavior in shopping. The purpose of this research is to find out daily needs during the Covid-19 pandemic. This research is a quantitative study in which a systematic empirical investigation of phenomena that can be observed using statistical, mathematical, or computational techniques is carried out. Predefined and highly structured data collection techniques are a major factor in quantitative research design when associated with positivis. this study shows what factors influence buyers' interest in buying a product at Online Groceries during the pandemic. And from the results of our research shows that one of the accepted and most significant factors influencing buyers' interest in buying at Online Groceries is from their Effort Expectancy

Tailoring elastomeric meshes with desired 1D tensile behavior using an inverse design algorithm and material extrusion printing

Additive Manufacturing (AM) is a highly attractive technology in the production of medical devices due to its capability to tailor product functionalities in line with a person's complex body structure. AM can resolve the chronic discomfort of body-supporting devices felt by people, especially those that suffer from imprecise fits, inconvenience with adjustments required in these devices to fit the body, or limitation of body movements to normal operating ranges. To enhance the user experience of those who wear medical devices, elastomeric meshes with programmed “waves” can be additively produced to enable an adjustment of the tensile stiffness in small-strain and large-strain sections. In this study, we demonstrate a method by which to adjust the stiffness transition point from low small-strain stiffness to high large-strain stiffness of additively manufactured sinusoidal and semicircular elastic fibers and determine the key design factors for transition points. Mechanics model predicts the 1D tensile behavior and experiments with controlled mechanical testing verifies the model. We reveal the major design factors that can induce the difference in the stiffness akin to on-off before and after transition. In addition, we produce meshes by the superposition of different wavy fibers, leading to multi-transition tensile behavior and thus expanding the area where mechanical properties can be controlled. An inverse design strategy is developed to improve the utility of an elastomeric mesh which enables the facile customization of the mesh with desired properties. Finally, we demonstrate that users can implement desired functions - not only the size but also the degree of body restriction - through proper settings by producing locally tailored wearable mesh-aid devices. • We clarify the major design factors for tailoring the nonlinear tensile behavior of a material extruded wavy elastomeric fiber. • Wavy fibers can transit their tensile stiffness to 1,400 fold in maximum at transition points. • Overall 1D tensile behavior of a mesh is the superposition of composed wavy fibers. • Inverse design accompanied by additive manufacturing well duplicates the targeted non-linear tensile behavior.

능동댐핑 영-극점 상쇄 BLDC모터 속도 제어기를 위한 경사 하강법 기반 자동 동조 알고리즘 설계

This paper presents an auto-tuning mechanism for major design factors adopted for the active damping pole-zero cancellation Brushless DC Motor (BLDCM) speed controller. The proposed auto-tuner is designed to seek the minimum point of the steepest gradient method-based controlled error’s cost function. Moreover, the proposed solution employs the compensation term (σ-modification) to assign the stable pole to the auto-tuner dynamics. The prototype dynamo system, which includes the 500W BLDCM as the test motor, verifies the effectiveness of the closed-loop system driven by the proposed auto-tuner.

규격분석 및 AHP를 활용한 고령자와 장애인용 2인승 역 삼륜 자전거 안전성 연구

Objective:The aim of this study is to propose a safety design guideline for a tricycle tandem for two persons for the elderly and persons with disability through standard survey and dynamics simulation.<BR>Background: In this recent, the issue of leisure and quality of life for the elderly has become more important due to the aging population. It has been found that the elderly and persons with disability prefer to ride a tricycle outdoors as a leisure activity to enjoy with family and friends. Most of the tricycles they can enjoy together are imported products and have not been developed in consideration of the domestic use environment, so research on their safety is needed.<BR>Method: In this study, in order to propose a safety design guideline for a tricycle tandem for two persons, the Korean standard (KS) was investigated to derive, and 10 major safety design factors were derived from the four related standards. And the importance of safety design factors was analyzed using the AHP (Analytic Hierarchy Process) method. In addition to the dynamics simulation of steering, safety design guidelines for 10 major safety design factors have been proposed.<BR>Results: In the results of the importance analysis (AHP) between the 10 safety design factors derived through the survey of existing standards,

Sensifi: A Wireless Sensing System for Ultrahigh-Rate Applications

Wireless sensor networks (WSNs) are being used in various applications, such as structural health monitoring and industrial control. Since energy efficiency is one of the major design factors, the existing WSNs primarily rely on low-power, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">low-rate</i> wireless technologies, such as 802.15.4 and Bluetooth. In this article, by proposing Sensifi, we strive to tackle the challenges of developing <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ultrahigh-rate</i> WSNs based on the 802.11 (WiFi) standard. As an illustrative structural health monitoring application, we consider the spacecraft vibration test and identify system design requirements and challenges. Our main contributions are as follows. First, we propose packet encoding methods to reduce the overhead of assigning accurate timestamps to samples. Second, we propose energy-efficiency methods to enhance the system’s lifetime. Third, to enhance sampling rate and mitigate sampling rate instability, we reduce the overhead of processing outgoing packets through the network stack. Fourth, we study and reduce the delay of processing time synchronization packets through the network stack. Fifth, we propose a low-power node design, particularly targeting vibration monitoring. Sixth, we use our node design to empirically evaluate energy efficiency, sampling rate, and data rate. We leave large-scale evaluations as future work.

Assessment from a disciplinary approach: design and implementation in three undergraduate programmes

ABSTRACT The role of the academic discipline is a major factor in the assessment design and implementation in higher education. Unfortunately, a clear understanding of how teachers from different disciplines approach assessment is still missing; this information can lead to teacher training programmes that are better designed and more focussed. The present study compared assessment design and implementation in three programmes (sport science, mathematics, and medicine) each representing a discipline from 4 Spanish universities. Using a mixed-methods approach, data from syllabi (N = 385) and semi-structured interviews with teachers (N = 19) were analysed. The results showed different approaches to assessment design and implementation in each programme in two main axes: summative or formative purposes of assessment, and content-based or authentic assessment. Implications for further research are discussed.

Design Constraints and Scale Down Evolution in Advanced Semiconductor Packages

ABSTRACT Wafer fabrication (fab) technology has been scaling down for several decades but now faces many barriers to overcome in terms of technology as well as economy. Beyond Moore's law, the scaling becomes a question of how to cost effectively integrate more functions and achieve better performance. For this matter, the semiconductor industry is looking for packaging solutions using system-on-chip (SoC) or System in Package (SiP) technologies. In this paper, using a commercial mobile application processor (AP), design factors for package integration have been identified and the next level of integration will be proposed by design simulation. The commercial mobile AP package is a good candidate for identifying major design factors because it has evolved in both fab processing and package-level design over many years. Package platform has evolved from a single package to a stack die package and Package-on-Package (PoP) structure. As it is scaled down and interfaced more closely with memory, package technology has evolved but now faces various challenges in structure along with many design constraints. To address these issues, the major drivers and design challenges in package technology will be identified and future direction be proposed.

Investigating the Effect of High-Rise Buildings’ Mass Geometry on Energy Efficiency within the Climatic Variation of Egypt

Energy conservation is recently the most important issue all over the world, including in Egypt. Recently, the built environment of Egypt has experienced a dramatic change in its buildings’ typology, with more interest in constructing high-rise buildings. This in turn creates high demand for energy, as high-rise buildings are considered to be one of the most energy-consuming types of buildings. Egypt has a wide variety in its climatic conditions, with seven different inhabited climatic regions, and a further one which is uninhabited. Therefore, integrating the energy efficiency of a building as a major design factor in the early design stages of such a type of buildings is important. This article is concerned with investigating the effect of high-rise buildings’ geometrical shape on the building’s energy consumption within the different climatic regions of Egypt. Four building shapes (square, circular, rectangular, and ellipse) are examined. The long axe of the models is oriented to the north (“the optimum orientation within all regions”), with a window-to-wall ratio (WWR) of 30%. The performance of these models is studied in seven cities representing the inhabited Egyptian climatic regions using simulation software, DesignBuilder, with the EnergyPlus simulation tool. Study findings revealed that adjusting the geometric form of the building significantly affects energy consumption and thermal comfort with climatic variation. The most compact shape, circular, was the most suitable geometrical shape in four regions out of seven. The ellipse shape was found to be the most suitable mass geometry within two other regions, while the square shape was found to be effective in only one region. The results of this research indicate that designers should not use the rectangular shape anywhere across Egypt.

Sustainability at an Urban Level: A Case Study of a Neighborhood in Dubai, UAE

The United Arab Emirates is witnessing enormous growth and the sustainability attitude has become one of the most important priorities in this development. This paper aims to optimize the environmental sustainability of the Emirate of Dubai communities by adopting an existing community as a case study. The investigation of the case study is looking at sustainability levels that consists of two major factors in neighborhood sustainable design, such as livability and thermal performance. The strategy of enhancing and optimizing the communities’ sustainability starts with an approach to the applicable modifications and solutions to the existed community master planning, where the modifications cover the two main urban design variables; (a) building design, and (b) open and landscape areas. The effect of the adopted scenarios is analyzed to find the improvement in environmental and thermal performance. The study has adopted two computer software packages, namely CityCAD and Integrated Environmental Solutions—Virtual Environment (IES-VE), to undertake the assessments. Furthermore, factors of urban sustainability are evaluated using the United States Green Building Council (USGBC)’s Leadership in Energy and Environmental Design (LEED) neighborhood assessment tool. The results have shown that the environmental sustainability levels can be increased after the adoption of certain suggested scenarios, in order to mitigate the likely weakness indicated in the livability aspects, covering land-use diversity, accessibility, transportation system, green and landscape areas, and energy efficiency, and the case study community can be turned toward “Sustainable Community” by implementing recommended actions and modifications.

Micro and Macro Structural Investigations on Welded Joints of Composite Truss Steel Concrete Beams

The results of an experimental test campaign including micro and macro investigations on welded joints typically used in Composite Truss Steel‐Concrete beams are presented. The research was carried out with the aim of assessing the relevance of welding effects on the mechanical performance of different typologies of steel grades that can be used to realize the internal truss steel system, connected to the bottom steel plate used with the double structural and formwork function. Two different steel typologies were adopted for the steel truss: the “traditional” structural micro‐alloyed steel, normally used for composite steel‐concrete elements, and the typical reinforcing steel with TempCore® structure, achieved through the application of two‐phase thermomechanical treatment of quenching and tempering. The interest in the possibility of adopting reinforcing steel for the internal truss arises from its potential economic benefit, finding its justification in the intermediate condition in which this structural typology lies, between composite steel‐concrete and ordinary reinforced concrete buildings. Welding has a strong impact on such reinforcing steel material, resulting in relevant drops of ductility and brittle failure usually taking place in correspondence of the heat‐affected zone. So, it is advisable to refrain from using such steel grade, especially in constructions in seismic‐prone areas, where ductility is a major influencing and design factor.

Significance evaluation of performance factors on horizontal spiral-coil ground heat exchangers

Ground-coupled heat pump systems using horizontal spiral-coil ground heat exchangers (HSGHE) are being utilized for an increasing number of applications due to the efficiency in terms of thermal performance. To optimize design accuracy and thermal performance, significant design factors of HSGHEs should be identified. Thus, this study investigates the effects of influential factors on the thermal performance of HSGHEs through sensitivity analysis. Numerical models were established with respect to the operation of HSGHEs using the finite element method. Variance-based sensitivity analysis was conducted using the numerical results to quantitatively evaluate the overall effects, which include the main effects as well as interaction effects between the design factors. Furthermore, case studies of two different regions were applied to the sensitivity analysis to compare the effects of regional climate factors on the order of significance of the input factors. As a result, ground thermal conductivity, installation depth, and inlet fluid temperature were determined as major design factors. On the other hand, the order of significance of the major factors was found to be dependent on regional climate factors. This result implies that it is necessary to consider different critical factors of HSGHE design according to the ambient conditions of the installation region.

An analysis of users\u2019 preferences on learning management systems: a case on German versus Spanish students

The recent advancements in information and communication technologies have altered instructional contexts and re-shaped them into smart learning environments. One of the most common practices of these environments are learning management systems (LMS) where the learners and instructors utilize a software platform to fulfill, support and manage instructional activities around predefined objectives. Successful implementations of LMS have brought a variety on its usage from different cultures, genders, age groups or schooling levels. Hence, this study focuses on understanding the role of culture on LMS design, in along with the effects of gender, age and school year variables. The study participants were German (n = 83) and Spanish (n = 83) university students attending a fully online course offered by a South Korean university. At the end of the course, the students were asked to fulfill a survey on effective LMS design by pointing which features of LMS were more important for them. The survey included twenty questions on four major design factors; content management (six items), ease of use (five items), communication within LMS (four item) and screen design (five items). The dataset was analyzed by non-parametric statistical techniques around four variables on four dimensions (and their related survey questions). The most important result was insufficiency of one unique LMS design for all students which demonstrates the necessity of student demographics tailored smart systems. Additionally, age and gender variables were not making significant differences on LMS design as much as culture and school year variables. The study also revealed that while German students would appreciate goal-oriented individual learning, Spanish students would value process-oriented group learning with active communication. Furthermore, many features of LMS were highly valued by the freshman students more than other levels. The paper discusses these variables with possible explanations from the literature and depicts implementations for future design practices.

압축 공기를 사용한 소형 이젝트의 진공 흡입 성능 평가 요인에 관한 연구

This study analyzed the internal flow structure of a small ejector and the major design factors that affect suction force. The ejector had a limited total length of 45 mm, and the primary nozzle had a diameter of 1 mm. This study investigated the effect of the main parameters on optimum nozzle opening ratio based on injection flow as well as the influence of the mixing chamber design on vacuum suction performance. The second nozzle had a significant effect when the diameter was 18 mm. Other parameter values were studied to identify design elements that determine the shape of the mixing chamber. The effect of the pad opening gap and the change in ambient pressure on the control state of the inflow ratio and the possibility of non-contact gripping were also examined.

Prediction the Strength of Fibered Reinforced Concrete Pavement Using Response Surface Methodology: Parametric Study

Due to the pattern of load distribution in terms of load-carrying capacity, strength considered the major factor in design of pavement. For design the thickness of the rigid pavement, modulus of rupture (flexural strength) values used in the design procedure. The main purpose of the present study is to design optimum Eco-friendly concrete mixtures containing different amount of Fibers used in rigid pavement matching Iraqi requirements by using Response Surface Methodology (RSM). The experiments were designed using a thirty mixtures with four factors, namely, the cement content 300,400 and 500 kg/m3, Steel fiber (0,0.075, and 0.15 Vol.%), three different volume of Polypropylene fiber (0,0.35 and 0.7 Vol.%), and 0, 5, and 10% Silica fume by weight of cement. The results stated that cement amount and steel fiber volume are the higher factors affecting the mechanical properties flowed by pp fiber and silica. Furthermore, a good correlation between the adopted variables and mechanical properties (compressive and flexural strength) was found through statistical models, where the correlation coefficients (R2) for all models were greater than 0.90. Optimal components to design concrete mixtures used in pavement that having compressive strength of (>30 Mpa) and flexural; strength of (> 4.1 Mpa) are cement 375 kg/m3, silica fume 0.002%, steel fiber 1.44e-005 (Vol.%), and PP fiber 4.53e-006(Vol.%).

The Effects of Rainfall Intensities and Duration on SCS-CN Model Parameters under Simulated Rainfall

The Soil Conservation Service curve number (SCS-CN) method has been widely used in rainfall-runoff modelling; however, the direct effects of rainfall intensities and duration, which are major factors in hydrological engineering design, on its parameters (initial abstraction ratio (λ) and potential maximum storage (S), the latter is transformed into curve number (CN)) have seldom been studied. In this study, we chose simulated rainfall experiments on runoff plots (30 mm/h, 180 min; 60 mm/h, 90 min; 90 mm/h, 60 min) to obtain synchronized rainfall-runoff data and calculated the parameters using general model fitting and event analysis methods every ten minutes throughout the duration. The results indicate that the parameters changed with rainfall intensities and duration. S decreased as the rainfall intensities increased. Under the same rainfall intensity, the S increased with the duration overall. The corresponding λ changed with rainfall intensities and duration, and has no obvious relationship under different rainfall intensities. Initial abstraction in the event analysis method is the same as the actual situation and we chose these parameters obtained with the event analysis method as our selected parameters. These selected parameters and the parameters obtained using Fu et al.’s method which was based on the standardized procedure in NEH-630 were evaluated by the Nash–Sutcliffe efficiency (NSE), the percentage deviation coefficient (PBIAS), and the ratio of the root mean square error to the standard deviation of measured data (RSR). The results show that the statistics for the selected parameters satisfied the evaluating standard, and have a better value, while the statistics for the parameters obtained by Fu et al.’s method declined as the rainfall intensity increased, and PBAIS was out of the standard range under 90 mm/h rainfall intensity condition. This indicates that the rainfall intensities and duration have important effects on the parameters of the model, and the parameters vary dynamically with the rainfall intensity and duration. These results could be useful for hydrological design in which engineers consider the return period (i.e., rainfall intensities and duration).

Energy Efficient Synchronous Media Access Control for Wireless Sensor Networks

The technological advancements have brought a revolution in the field of communication, especially in the area of wireless communication. It has made the deployment of WSNs possible which comprise of a large number of low-power and low-cost sensor nodes to perform the task of sensing, processing, and communication. WSNs set stringent requirements for network lifetime, resource constraint, application specific behavior and they are highly dynamic in nature. The one factor which affects the most is the network lifetime and it requires the energy efficient operation to be performed. This article aims at providing researchers a clear understanding and deep insight into the selection MAC protocols which is one of the major design factor while establishing WSNs or developing an energy efficient routing protocol for WSNs. The article presents a systematic review of various low duty cycle syncronous MAC protocols along with an in-depth analytical comparison and discussion based on various performance metrics.

Development of phased array ultrasonic system for detecting rail cracks

In this study, a phased array ultrasonic system for detecting rail cracks (PAUSR) was developed which consists of two phased array (PA) ultrasonic transducers, a water tank, a display monitor, a battery, a commercial 64 channel PA board, and its control software. To accomplish this, the acoustic fields and crack detection images of newly developed PA ultrasonic transducers were simulated and analyzed by the CIVA (CIVA 2016, NDE CIVA, USA) software. The major design factors for the PAUSR is the capability of evaluating crack size (over 2 mm), generating proper acoustic fields in the rail and easy and safe handling for operators. For the performance test of the designed PA ultrasonic transducer, Non-destructive Characterization and Verification of Ultrasonic Phased Array Equipment, Part 2: Probes (EN ISO 18563-2:2017) was conducted. In addition, artificial crack detection images were simulated by the CIVA software, and an experiment under the same CIVA simulation conditions was also performed for comparison purposes. For the last verification, natural defective specimens with bolt-hole star-cracking, longitudinal vertical cracking and welding defects were scanned by the developed PAUSR, and its results were analyzed and compared with the radiographic testing (RT) and CIVA simulation outcomes.