Effects Of Design Factors Research Articles

Impact of architectural design strategies on the indoor natural ventilation of public residential buildings in Singapore

The architectural design pattern of the public residential buildings developed by Housing and Development Board (HDB) of Singapore has evolved gradually throughout the past decades. However, the fact is that although the new generations of HDB blocks built in recent years are designed to be modernized, the usage of air-conditioning has been increasing in comparison with the old generations. This study aims to investigate the ventilation performance of HDB blocks built in different generations from a historical view. By conducting computational fluid dynamics (CFD) simulations on five typical blocks built in different generations, the area-weighted wind velocities in various rooms of the target units were obtained. The effects of design factors on wind velocity ratio (VR) in corresponding spaces were analyzed and compared. The results show that the old generations with parallel plan layouts generally facilitate cross-ventilation while the new generations with centralized plan layouts usually generate single-sided ventilation which is more sensitive to incoming wind direction. Meanwhile, the window-to-wall ratio and shading depth of the studied facades were validated to have positive and negative relations to the VRs respectively. Though the correlations are insignificant, they show significant disparities between the scenarios under different incoming winds.

Effects of hollow fiber packing density and housing shape on the albumin filtration performance of CRRT filters

Continuous renal replacement therapy (CRRT) has become the most commonly used acute blood purification therapy for critically ill patients. As a key point of extracorporeal blood circulation, the CRRT filter plays a decisive role in therapeutic efficacy. However, few in vitro studies have been conducted on CRRT filters, particularly concerning the effects of design factors on filter effectiveness and safety profile; no comprehensive evaluation system has been established. Here, we designed nine CRRT filters with various combinations of hollow fiber packing density (PD) and housing shape (effective hollow fiber length (L) and inner housing diameter (D) ratio (L/D ratio)) and introduced a high-frequency sampling pressure monitor to accurately monitor small changes in transmembrane pressure (TMP) and ultrafiltration rate (UFR) over time. We also used concentration polarization mass transfer resistance (Rc), change in sieving coefficient (S) of albumin over time, and amount of albumin removed (Mfld) to investigate the effects of two design factors on albumin filtration performance and analyze the mechanism of protein filtration performance over time, thereby establishing a comprehensive in vitro evaluation system to explore the safety profile of CRRT filters. Our results showed that the nine CRRT filters designed with different combinations of PD (50%, 55%, and 60%) and L/D ratio (2.9, 5.3, and 9.3) were able to maintain stability in terms of hemodynamics and water permeability; the lowest Mfld was PD = 60% and L/D ratio = 9.3, which indicates that design factor optimization can effectively control albumin filtration, thereby improving the safety profile of CRRT filters.

Planning and Design of a Flood Resilient Building Based on Impact Study

Over these years, the world has endured large number of natural disasters. Among them the most disastrous one is flood. Flood can cause a potential treat to both life and property. The influence of global warming is one of the major causes that appears to worry the world, especially the effect of flood happening at the river side that causes potential loses. It difficult to living against water, but it possible to live with water level rising. The rising water occupies the land surface. The land surface taken away by the rising water. The only way to live with rising water is by constructing houses on the water. Amphibious structures are becoming more popular among the people in Kerala. Amphibious structures are buildings that sit on dry land like ordinary buildings, except there is a flood. An in-depth study of permanent housing has done by studying the various ways that flood events affect housing in order to identify guiding criteria that flood resilient housing should address. Furthermore, it is needed to differentiate between flood zones since housing should respond and resist to flooding according to predicted flood characteristics. This project incorporates study of various flood resistant housing projects and the most effective design factors are identified and a new proposal is suggest for the resilient housing. The housing proposal through this study stands well within the boundaries of sustainability, and address the problems of flood related issues of housing in a most efficient way.

CFD-Study of the H-Rotor Darrius wind turbine performance in Drag-Lift and lift Regime: Impact of Type, thickness and chord length of blades

The high power coefficient of the Darrius vertical axis wind turbine lift regime has prompted researchers to concentrate their efforts on this regime, despite the fact that these turbines suffer from major problems in the drag-lift regime. In the present study, in addition to exploring the performance of the Darrius type wind turbine at blade tip speeds Ratio above 1, the effect of design factors on its performance at TSRs below 1 is also investigated. The results were extracted from numerical analysis recruiting Fluent software and the k-w SST turbulence model. The effect of blade type, thickness, and chord length on turbine performance has been investigated. The blade angle of attack (AOA) at TSR less than one was calculated using a new equation, and the results were evaluated. The numerical study of the Darrius wind turbine showed that increasing the chord length for symmetric and asymmetric airfoils from 0.1 to 0.2 m enhances the turbine performance in drag-lift regime, whereas decreasing chord length improves turbine performance at higher TSRs. The blade with a curvature of 4 % and a chord length of 0.1 m has the best performance at TSR 2.25. Increasing the thickness from 18 to 22 % of chord length exerts a negative influence on the turbine's performance in both regimes, and at lower TSRs, NACA0018 airfoil with a chord length of 0.2 m was of the optimum performance in the drag-lift regime.

Effect of design factors on drivers’ understanding of variable message signs locating traffic events

BackgroundThis article addresses how to combine three elements (a pictogram, an arrow, a city) in a variable message sign (VMS) to locate temporary events (e.g., “congestion before Milan”). We adopted the G1c stack model as a design template, an Advanced Directional Sign (ADS) recommended by the 1968 Convention to locate cities, which can be easily adapted to modern VMS. However, as most of the VMS in operation are not full-matrix, we have also adapted this design to more restrictive display conditions. This adaptation critically concerned the arrow function on the message that either points up broadly (generically, as in G1c) or connects with the city more specifically (explicit). Although G1c reads top-down like a verbal text, previous studies indicated drivers’ preference for bottom-up landmark order in VMS, so both ordering criteria were compared in the present study. MethodsThe experiment involved 99 people (70 drivers and 29 drivers in training). Participants were informed that they would see various VMS reporting certain events (e.g., congestion) related to one of four cities along the road. Their task was to identify the event location (before, after the city) after seeing blocks of two consecutive messages (first a complementary message, then the target message), limiting their response to the content of the second message. Three design-focused factors were tested: typographical alignment (left or centre), landmark order (bottom-up or top-down), and arrow function (explicit or generic). The rate of correct location answers was the dependent variable. ResultsResults revealed that comprehension varied greatly depending on the arrow’s function and the placing of elements. In the explicit-arrow messages, comprehension was good both in the Top-down and Bottom-up conditions, but in the generic-arrow messages, only in the Bottom-up condition was comprehension good. Likewise, understanding was better in the Before condition than in the After condition in all combinations of Landmark order and Arrow function conditions. In general, left alignment of the central column elements of the VMS improved comprehension respective to centred alignment. Finally, the complementary message factor had an effect under certain circumstances. Practical implicationsThe messages displaying a generic arrow (following the G1c model) were better understood when the landmarks were ordered bottom-up, not top-down. In addition, explicit-arrow messages were better understood per se (in the absence of a complementary message) than generic-arrow messages. Overall, this work suggests that improving our understanding of how thought processes and design features relate to each other can contribute to safer driving nationally and internationally.

NUMERICAL AND EXPERIMENTAL INVESTIGATION ON EFFECT OF DESIGN FACTORS ON SHEAR PROPERTIES OF ADDITIVELY MANUFACTURED TETRA-ANTI-CHIRAL CELLULAR METAMATERIAL

This paper presents numerical and experimental investigation on the effect of design factors on mechanical properties of tetra-anti-chiral cellular metamaterial under shear loading. Two design factors namely cylinder radius and strut thickness, and three response characteristics including shear strength, modulus and specific energy absorption (SEA) of structure are considered in the present study. Finite element analysis (FEA) of CAD models of structures is performed using non-linear mechanical simulation. For experimentation, specimens are manufactured using material extrusion technique of additive manufacturing. A novel fixture is designed and manufactured for quick loading and unloading of structures for shear testing. It is observed that with decrease in cylinder radius, strength and modulus increases, but SEA decreases. However, all three responses increase with increase in strut thickness. Optimization of design factors is performed using grey relational analysis to maximize responses. Furthermore, predictive models of responses are developed using regression analysis.

Effects of design factors on the driving-out force of the steel shaft in a shrink-fitted ceramic roller

Shrink-fitted ceramic sleeve rollers are recently developed to be used efficiently in steel manufacturing industries. However, at times, the shaft moves out of the ceramic sleeve during cyclic loading because only small a shrink-fitting ratio can be applied. Given that the driving-out forces Fd can be calculated as the contact force occuring at the stoppers, this study considers the simplified two-dimensional model with stoppers. Then, the effects of several design factors on the driving-out force are discussed by varying the friction coefficient, shrink-fitting ratio δ/d, shrink-fitted length, and Young’s modulus of the inner shaft. Results show that the driving-out force takes a maximum value of approximately δ/d = 0.3×10−3 and then sharply decreases to Fd = 0 at approximately δ/d = 0.45×10−3. The shaft moving out can be prevented by designing a suitable stopper with sufficient strength for maximum value.

Parametric Study on the Flow Profiles of Vertical Sinter Cooling Bed Using the DEM and Taguchi Method for Waste Heat Recovery

To comprehensively understand the effectiveness of external factors on flow characteristics and realize particle flow distribution evenly in bulk layers is an essential prerequisite for improving the performance of heat transfer in vertical sinter cooling beds (VSCBs). The numerical discrete element method (DEM) was applied to investigate external geometric and operational factors, such as the aspect ratio, geometry factor, half hopper angle, normalized outlet scale, and discharge velocity. Using the Taguchi method, a statistical analysis of the effect of design factors on response was performed. In this study, we focused more on external factors than granular properties, be remodelling the external factors was more useful and reliable for actual production in industries. The results showed that the most important factor was the aspect ratio, followed by the geometry factor, normalized outlet scale, half hopper angle, and discharge velocity for the dimensionless height of mass flow. In terms of the Froude number, the most influential factor was the normalized outlet scale with a contribution ratio of 33.81%, followed by the aspect ratio (22.86%), geometry factor (17.73%), discharge velocity (17.73%), and half hopper angle (11.83%).

Explaining the variation in the attained power of a stepped-wedge trial with unequal cluster sizes

BackgroundIn a cross-sectional stepped-wedge trial with unequal cluster sizes, attained power in the trial depends on the realized allocation of the clusters. This attained power may differ from the expected power calculated using standard formulae by averaging the attained powers over all allocations the randomization algorithm can generate. We investigated the effect of design factors and allocation characteristics on attained power and developed models to predict attained power based on allocation characteristics.MethodBased on data simulated and analyzed using linear mixed-effects models, we evaluated the distribution of attained powers under different scenarios with varying intraclass correlation coefficient (ICC) of the responses, coefficient of variation (CV) of the cluster sizes, number of cluster-size groups, distributions of group sizes, and number of clusters. We explored the relationship between attained power and two allocation characteristics: the individual-level correlation between treatment status and time period, and the absolute treatment group imbalance. When computational time was excessive due to a scenario having a large number of possible allocations, we developed regression models to predict attained power using the treatment-vs-time period correlation and absolute treatment group imbalance as predictors.ResultsThe risk of attained power falling more than 5% below the expected or nominal power decreased as the ICC or number of clusters increased and as the CV decreased. Attained power was strongly affected by the treatment-vs-time period correlation. The absolute treatment group imbalance had much less impact on attained power. The attained power for any allocation was predicted accurately using a logistic regression model with the treatment-vs-time period correlation and the absolute treatment group imbalance as predictors.ConclusionIn a stepped-wedge trial with unequal cluster sizes, the risk that randomization yields an allocation with inadequate attained power depends on the ICC, the CV of the cluster sizes, and number of clusters. To reduce the computational burden of simulating attained power for allocations, the attained power can be predicted via regression modeling. Trial designers can reduce the risk of low attained power by restricting the randomization algorithm to avoid allocations with large treatment-vs-time period correlations.

Parametric design analysis of meridional deflection stresses in metal expansion bellows using gray relational grade

Unpredictable and uncertain failure of the bellows needs the attention of the designer toward maximum meridional deflection stresses generated on the U-shaped convolutions. Evaluation of these maximum stress points on the flexible convolutions is multifaceted. This paper deals with the identification of these stresses induced on the bellows convolutions by analytical and experimental methods. Further, the influence of the pivotal design parameters on meridional deflection stresses is studied mainly in two aspects: (1) effect of number of convolutions (N) and pitch diameter (dp) on the meridional deflection stresses and (2) the determination of the optimized design parameters to reduce the stress levels using effective multi-response gray relational grade (GRG) optimization technique. Three bellows of stainless steel material (Grade SS321) are used for the experimentation with a different number of convolutions (N) and pitch diameters (dp). The optimal design parameter setting is found by using GRG analysis through ANOVA and regression mathematical model. The effect of design factors on GRG is analyzed. Besides, using GRG, the regression model enhances to give alternative optimal solutions; in turn, it increases the designer’s choice for the selection of the parametric levels. In the confirmation test, it is seen that the average improvement in GRG for all selected Taguchi orthogonal runs is 23%.

Effects of Design Factors on Drag Forces and Deformations on Marine Aquaculture Cages: A Parametric Study Based on Numerical Simulations

In Japan, the marine aquaculture net cage has an important role in farming pacific bluefin tuna farming in oceans, and the design of the net cage needs to ensure robustness against hostile oceanic conditions. Accordingly, this study focuses on the drag forces and the cage volume of the net cage, and on their variations induced by different design parameters (netting solidity ratio, netting height, and bottom weight). A series of parametric studies on drag force and deformation of the net cage was conducted using a numerical simulation model. Accordingly, the contribution of each parameter to the drag and volume was analyzed using a generalized additive model. The results indicate that the bottom weight had the highest contribution to the holding ratio of the cage volume, whereas the netting height had the highest contribution to the drag coefficient of the net cage. Finally, a fast prediction model was created by a backpropagation (BP) neural network model and was examined for the accurate prediction of the objective variables.

Effects of design factors on the cyclic response of sloped RBS moment connections

Abstract Non-orthogonal structural framing is essential in modern architectural design; and sloping beams are often required in structures, particularly at the roof level. In this paper, a sensitivity study is conducted to statistically evaluate the effect of beam slope angle along with different design factors on the cyclic response of Reduced Beam Section (RBS) moment connections. To this end, 3D finite element models are developed and verified based on two sets of experimental studies. The verified models are then used to carry out a sensitivity analysis employing the design of experiment (DOE) method. Thirteen design factors, related to the connection material or geometry, are considered. The analyzed RBS connection models, which are generated based on DOE, conform to the AISC seismic design requirements for RBS connections in special moment frames. The cyclic response of RBS connection models is assessed by evaluating different response variables, including initial stiffness, rupture index, plasticity index, moment capacity, yield moment, hysteretic energy dissipation, and strength degradation rate. The results show the relative significance of each factor and interaction effects on the cyclic response of RBS connections. Based on the results, slope angle and beam depth are the most significant factors influencing all the response variables. The beam slope angle and beam depth both have increasing effects on the cyclic response characteristics. With up to 80% contribution, the effect of beam slope angle is found to be significant and greater than the beam depth effect. RBS connections with smaller beam slope angle and beam depth experience lower strain demands and less potential for fracture.

Evaluation of contact fatigue risk of a carburized gear considering gradients of mechanical properties

Carburized gears are widely used in geared machines such as wind turbines. Contact fatigue problems occur in engineering practice, reducing reliabilities of machines. Contact fatigue failures are related to many factors, such as gradients of mechanical properties of the hardening layer. In this work, an elastic-plastic contact model of a carburized gear is developed based on the finite element method to evaluate contact fatigue failure risk, considering variations in hardness and strength. The Dang Van multiaxial equivalent stress is calculated via Python coding within the Abaqus framework. The gradient of yield strength along the depth from case to core is considered. The concept of local material fatigue failure risk is defined to evaluate the probability of pitting failure. The effects of design factors, such as the case hardening depth (CHD), surface hardness, and contact pressure on fatigue failure risk, are studied. As the CHD increases or the surface hardness decreases, the risk of deep spalling failure reduces. The increase in surface hardness leads to a decreased risk of pitting failure, while the variation in CHD hardly affects the pitting failure risk.

Wear behaviour of Al-SiC metal matrix composite under lubricated environment

The present study investigates the wear behaviour of silicon carbide based aluminium metal matrix composite under lubricated environment. The composite reinforced with 2.5% SiC by weight was prepared through stir casting method. The experiments were conducted on a pin on disc type tribotester under lubricated condition using five levels of load and sliding velocity varying from 10 N to 90 N and 0.26 m/s to 0.78 m/s respectively. The experiments were carried out based on the combination available in Taguchi’s L25 orthogonal array (OA). Then the effect of design factors on wear rate was investigated. Taguchi’s method was implemented to find the optimal parameter combination. Statistical analysis was made to find out the relative influence of design factors on wear rate. Finally, field emission scanning electron microscopy (FESEM) was carried out to determine the wear mechanisms.

Evaluating the Effects of Earthquake Wave Propagation on Buried Curved Pipes Using Static Analysis

Pipelines as lifeline play a key role in water, gas, and oil delivery. One of the effective factors in the design of buried pipes is fault existence on its path. One of the other effective factors in the pipeline design is the propagation of earthquake waves along it. Wave propagation means that the different parts of the pipes are vibrating with different values of accelerations due to earthquake wave propagation. This phenomenon can cause great stress and strain in the pipes. For determining the response of the burial pipelines due to wave propagation, a specific time history analysis is necessary using an earthquake accelerogram, which is highly complicated. The present study was conducted to evaluate the effects of earthquake wave propagation on the seismic response of curved buried pipes using simple method. In this method, it is assumed that during the earthquake, the burial pipe in the soil is deformed the same as its surrounding soil. Therefore, for seismic analysis of the pipe, the displacement record is used instead of acceleration record. The results showed that the earthquake wave propagation affect the seismic performance of buried pipelines considerably. Hence, it can be claimed that a decrease in the wave velocity in the soil would result in an increase in the longitudinal component of strain in the pipeline. Moreover, it was found that the curvature angle of 30° would have the greatest effect on the seismic response of pipelines. Finally, it was demonstrated that the longitudinal component of vibration has a greater effect on pipeline design compared to other components of the vibration.

A method to generate design-sensitive occupant-related schedules for building performance simulations

Despite the purported benefits of occupant behavior (OB) models in simulating the effect of design factors on OB and vice versa, there are challenges associated with their use in building simulation practice due to the additional time and computational requirements. To this end, this article presents a method to incorporate these models in building performance simulations (BPS) as design-sensitive schedules. As an example demonstrating this method, more than 2,900 design alternatives of an office were generated by varying orientation, window to wall ratio (WWR), the optical characteristics of windows and blinds, and indoor surface reflectances. By using daylight simulations and stochastic OB modeling, unique light use schedules were generated for each design alternative. Two data-mining algorithms were then examined to identify the relationship between light use schedules and design parameters. Results indicated that WWR and building orientation had the strongest effect on light use schedules. These findings are relevant for building energy codes, as they provide an intermediate approach to incorporating design-sensitive schedules as BPS inputs. These design-sensitive schedules are expected to be superior to default ones currently specified in codes and standards, which ignore the effect of design factors on OB, and ultimately on energy consumption.

A numerical investigation of preheated diluted oxidizer influence on NOx emission of biogas flameless combustion using Taguchi approach

The present investigation submits an analysis about the influence of preheated diluted oxidizer parameters on NOx emissions from a biogas flameless burner. The design parameters and their levels were diluting species, N2 and CO2, oxygen concentration of 5, 7 and 10% and preheated air temperature at 900, 1100 and 1300 K. An L18(2132) Taguchi orthogonal array was employed to design the test plan for numerical simulations. The results reveal that an increase in oxygen concentration leads to more NOx emissions. The same result is obtained by increasing preheated air temperature. Also, air dilution with N2 gives better result for reducing NOx emission compared to CO2 dilution method. As well as, according to the ANOVA (analysis of variance), the most effective design factors on NOx emission are oxygen concentration and then preheated air temperature with around 57% and 32% contribution, respectively, which indicates NOx emission can be successfully enhanced by controlling these parameters.

Effects of Design Factors of HDFS on I/O Performance

Four major design factors of HDFS, the block size, the number of data nodes, the number of client processes and replication factor are investigated to find out the effects on the I/O performance of HDFS by performing experiments in a real physical HDFS infrastructure consisting of 64 Hadoop data nodes of Intel i9 based blades. The block size is observed to be optimal when it equals to about 1Gb or 128MB that is the amount of the data the hard disk drive device can effectively input and output for 1 second in most of today’s off-the-shelf computers. Sophisticated allocation strategy is required to determine the number of mappers and reducers as the number of data nodes increase because the overall performance is influenced in complicated manner by the number of raw data blocks of the job to be processed, the processing time of the blocks for each node and the overhead of shuffling. Experiments shows that Hadoop distributes the work properly that the number of clients does not have a significant impact as the number of clients increases. There is little delay in copying the replica because replication is done in pipelined manner although the network is overloaded.

Design specifications for Multi-Function Consoles for use in submarines using anthropometric data of South Koreans

These days, the importance of Human Factors and Ergonomics (HF&E) when producing military systems is being increasingly recognized. However, existing literature and guidelines have predominantly focused on the minimum requirements rather than optimal parameters when HF&E departments have associated with designers and engineers. Thus, in this paper, we investigate a design process suggesting optimal parameters for multi-function consoles (MFCs) installed in submarines using anthropometric data for Koreans. The design procedure utilized in this paper follows “clarification”, “analysis”, “design”, “simulation”, and “evaluation”. For the clarification step, effective design factors taking into account operators’ postures were identified via the task analysis. During the analysis, HF&E criteria as well as the ethnic characteristics of Koreans were investigated to evaluate the minimum requirements of design factors. The anthropometric data from the Size Korea project, which includes measurements from a total of 14,016 people from the Republic of Korea, were utilized to suggest appropriate ranges for the design parameters. Design and simulation steps were iteratively preceded by evaluating the design specifications for their appropriateness through human simulation modeling. Finally, a full-scale mock-up was developed; 10 HF&E experts conducted the direction and detection tasks carried out by navy crews to evaluate reaction time as well as subjective comfort. Thus, with the results from this study, we were able to successfully suggest and validate the design specifications for submarine-mounted MFCs for Korean use by utilizing Korean anthropometric data.

Effect of design factors on the thermal environment in the waterfront area

As one of the complex underlying surfaces, the water body improved the local thermal climate in the surrounding area especially on water vapor diffusion and temperature. Therefore, this paper, taking the water effect and factor analysis as the research object, based on the CFD method, key factors were analyzed which influencing thermal and humidity environment in the waterfront areas. The factors mainly discussed in this paper are building type, building floor area ratio, embankment height, distance from water body, and landscaping. Each factor includes five levels. The results indicated that the influence scales of thermal and humidity environment were highly dependent on the geometry of ventilation gallery in the residential areas of the waterfront. The results also indicated that the temperature in area with the low plot ratio and large ventilation gallery was more easily affected by the waterbody.