Straight Layout Research Articles

Cu Clip-Bonding Method With Optimized Source Inductance for Current Balancing in Multichip SiC MOSFET Power Module

Cu clip-bonding is a promising packaging method for lower resistance, lower inductance, and higher reliability than wire-bonding. Previous studies only simply replace bond wires with Cu clips on an individual die. However, current sharing and thermal coupling issues among multichip modules are still big challenges in the clip-bonded silicon carbide (SiC) <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> power module. In this article, a novel source inductance optimization method is proposed. Extra modification paths (MPs) on Cu clips are used in this method. A clip-bonded half-bridge multichip SiC power module is designed and fabricated to verify the superiority of the method. In a simple straight layout, the distance between adjacent dies is large enough to avoid heat concentration and junction temperature differences resulting from the thermal coupling effect. The MPs structure on the Cu clip is designed to optimize the power source inductances. Parasitic circuit model and mathematical analysis are derived to demonstrate the features of proposed MPs. Simulations and experiments workbench are conducted to analyze drain current sharing performance. Derivation and simulation show the highest branch's inductance is reduced. Test results show the current imbalance and loss imbalance are relatively mitigated, which proves that the effect of power inductances imbalance is suppressed by the proposed optimization method.

Designing a warehouse internal layout using a parabolic aisles based method

Refined layout is a basis of warehousing efficiency. Straight aisle is a typical feature of current warehouse internal layouts. The purpose of this paper is to explore the possibility of using curve aisles for warehouse layout. By Choosing typical non-traditional layouts and transforming their inclined cross-aisle trajectory into parabola, two parabolic aisle layouts, parabolic Flying-V and parabolic Fishbone, are constructed. For unit-load warehouses, based on the morphological characteristic analysis and the parabolic types selection, the picking distance model and the cross-aisle length formula are presented. Interval Numerical Simulation Method (INSM) and Genetic Algorithms (GA) are adopted to solve the model respectively in order to verify the results. This research breaks through the realistic situation of straight aisle leading warehouse layout, and enriches the relevant layout theory. The calculation results of 100 warehouses with different sizes show that the picking distance of parabolic Flying-V could be reduced by 0.22-0.62 % compared with the straight layout, and the theoretical possible improvement space has been compressed by 2.42-12.26 %. Its length of cross-aisle is shortened by -0.03-3.10 %. The picking distance of parabolic Fishbone could be only reduced by 0.02-0.04 %. The theoretical possible improvement space has been compressed by 1.27-1.83 %. But its length of cross-aisle will increase by 4.63-19.50 % significantly. We believe that the layout of non-rectangular complex special-shaped warehouses based on curve trajectory aisles would become an important research topic. In addition, after some necessary modifications to the objectives and constraints, the proposed method in this paper may also be used for the arrangement of machines and devices in a workshop in principle.

Friction properties of micro/nanogroove patterns in lubricating conditions

Tribological properties can be improved by surface texturing; however, most of the conducted studies used microscale patterns. This study evaluated the lubrication properties of four different micro/nanogroove layouts (i.e., one straight layout and three different types of V-shaped layouts) created using the nanostripe fabrication technology. For each layout, microgrooves were arrayed at a pitch of 4 μm or 6 μm, and nanogrooves were formed on the ridge between these microgrooves. Friction tests were conducted at different loads and speeds using a single-crystal SiC disk as the counter specimen. We showed that patterns with 6 μm pitch microgrooves had a lower friction coefficient than those with 4 μm pitch microgrooves. The layouts with a higher ratio of nanogrooved area obtained a lower friction coefficient in high load and low speed conditions that are considered as boundary or mixed lubrication regimes.

The Significance of Wind Turbines Layout Optimization on the Predicted Farm Energy Yield

Securing energy supply and diversifying the energy sources is one of the main goals of energy strategy for most countries. Due to climate change, wind energy is becoming increasingly important as a method of CO2-free energy generation. In this paper, a wind farm with five turbines located in Jerash, a city in northern Jordan, has been designed and analyzed. Optimization of wind farms is an important factor in the design stage to minimize the cost of wind energy to become more competitive and economically attractive. The analyses have been carried out using the WindFarm software to examine the significance of wind turbines’ layouts (M, straight and arch shapes) and spacing on the final energy yield. In this research, arranging the turbines facing the main wind direction with five times rotor diameter distance between each turbine has been simulated, and has resulted in 22.75, 22.87 and 21.997 GWh/year for the M shape, Straight line and Arch shape, respectively. Whereas, reducing the distance between turbines to 2.5 times of the rotor diameter (D) resulted in a reduction of the wind farm energy yield to 22.68, 21.498 and 21.5463 GWh/year for the M shape, Straight line and Arch shape, respectively. The energetic efficiency gain for the optimized wind turbines compared to the modeled layouts regarding the distances between the wind turbines. The energetic efficiency gain has been in the range between 8.9% for 5D (rotor diameter) straight layout to 15.9% for 2.5D straight layout.

A consecutive heuristic algorithm for balancing a mixed - model assembly line type II using a (W-TAWH) model developed for straight and U-shaped layouts

The development of assembly lines in manufacturing systems has evolved due to consumer expectations and a growing and increasingly competitive global market. The assembly line balancing problem (ALBP) is well recognised in manufacturing and may arise when tasks are assigned to the workstation. In this paper, a problem statement is structured by assigning a task to a worker in a suitable workstation, subject to some constraints, in order to reduce the cycle time and improve performance. This is a new approach, based on worker and task assignment and is thus a worker – task assigned to workstation heuristic model (W-TAWH). It has been developed for straight and U-shaped models. The methodology is described as two stages, the input related data stage and assignment stage. Firstly, the focus is on combining precedence diagram and generating the sequence vector procedure. The second stage comprises development of comprehensive mathematical formulae for the consecutive algorithm to address the straight and U – shaped balancing problem, with minimization or maximation of relevant criteria. This generates performance evaluation criteria according to the number of tasks and workers assigned to the workstation, and these criteria are integrated into a single score using a desirability function approach. Finally, the performance of the developed algorithm is validated through a numerical example. We tested 24 alternative solutions and the fourth solution (1-4-1) achieved the highest score (0.726), which represented the following assignment variables: straight layout, minimum total number of successor tasks rule, and four workers. The performance evaluation is represented by the lower bound of cycle time and upper bound of efficiency.

Effects of building arrangement on flow and pressure fields generated by a solitary wave interacting with developed coasts

A series of laboratory experiments and Large-Eddy Simulation (LES) carried out to study the interactions of a solitary wave with arrays of blocks, representing idealized beachfront buildings positioned at different arrangements, show that formation of jet-type channelized flow significantly alters the flow hydrodynamics, delays wave breaking and influences the total loading on the blocks in the back row. The staggered layout yields a 30–60% increase in the maximum force on the block in the back row compared to those of the single-row and straight layouts while the latter creates the highest shielding effect. The total number of primary vortices forming around the blocks is proportional to the number of sharp edges of the blocks. The dimensions of the vortex tubes are controlled by the width of the block. Although vorticities were not directly measured, the critical phenomena are accurately represented by the simulated flow field which was thoroughly validated using observations and measurements.

Material-by-Design Synthesis of Conformal Miniaturized Linear Phased Arrays

In this paper, the design of high performance conformal radiating structures is addressed within the Material-by-Design ( MbD ) paradigm. Toward this end, a new synthesis technique based on the innovative integration of a generalized quasi-conformal transformation optics and a source inversion procedure is proposed to fit linear phased arrays to smaller and arbitrarily-shaped surfaces. To the best of our knowledge, it is the first time that a design methodology simultaneously achieves ( i ) a simplification of the antenna layout through the reduction of its aperture and number of elements and ( ii ) its conformal transformation in order to match the aerodynamics of the hosting structure without affecting the required radiation features. It is worth remarking that the synthesized architectures are not only conformal, but they also provide the same performances of larger and straight layouts that could not be directly fitted to the available support. Some representative results are shown and discussed in order to validate the effectiveness of the proposed MbD methodology, as well as to highlight its current limitations.

Balancing U-shaped assembly lines with resource dependent task times: A Simulated Annealing approach

The advent of Just-in-Time (JIT) and Group Technology philosophies has popularized U-shaped assembly lines, which help overcome many of the disadvantages, like line inflexibility, job monotony, large inventories, etc., typically associated with straight assembly lines. Although U-shaped layout has demonstrated its supremacy over the traditional straight layout, the problem of U-shaped assembly line balancing (ULB) is much more complex. The extant literature on ULB assumes that each assembly task requires a fixed (or no) equipment and a fixed number of workers. However, it is often desirable to reduce certain task times by assigning more workers or alternative equipments at a given workstation. The problem in such cases is to assign not only the task but also resource alternatives (number of workers and equipment type) to workstations. Research on such resource dependent U-shaped assembly line balancing (RDULB) is scarce. We address the problem of RDULB and propose a Simulated Annealing (SA) based metaheuristic, which gives optimal solution for most of the small-to-medium problem instances. For very large problems, while SA generates a good feasible solution within half an hour to 1.5h, Cplex is unable to find a single feasible solution even after 10 times the CPU time required by SA.

漂流物対策として防衝工を配置した津波避難ビルに作用する津波波力に関する水理実験

Refuge facilities are required to save human life from a tsunami. Fender piles around a refuge facility could be a countermeasure to protect the facility from tsunami driftage. Hydraulic physical model tests were conducted to investigate tsunami wave force on a refuge facility with fender piles. Although it was found that fender piles had potential of wave force reduction, it was strongly depended on a tsunami wave profile. Visibility of a refuge facility should be high for evacuees. But there is a possibility that fender piles could bring it to deterioration. So, relationship between the layout of fender piles and the visibility was studied qualitatively. It was deduced that straight layout of fender piles would give safety feeling to refugees in a refuge facility and staggered layout would provide it to evacuee approaching toward a refuge facility.

Low mass aluminium microstrips for data transmission in the Micro Vertex Detector of the P̄anda experiment

The Micro Vertex Detector is the innermost part of the P̄anda experiment and is constituted of pixels and strips. The design foresees a triggerless data acquisition and Topix is the current ASIC solution for the pixel readout. The low material budget and high expected data rate demand low mass cables for the high speed serial data transmission.The interconnections on the sensor module are implemented with differential aluminium microstrips; the first prototypes with a folded layout were produced and extensively tested for electrical functionality and radiation hardness. Cables with a straight layout were then prototyped and their performances evaluated; performed measurements include static and dynamic characterisations, also in combination with Scalable Low Voltage Signaling (SLVS) transceivers.

Effect of Strain Rate on Metal Flow Pattern in T-Section Extrusion Process

Extrusion is a deformation process used in metal sections fabrication. Metal flow pattern during extrusion process is of great importance. How circular initial section of billet changes to final section provides more details of extrusion process, and plays an important role in optimizing the extrusion energy. Extrusion in flat-faced die, without intermediate section, needs much more energy than is required for die having intermediate section. The aim of this study was to investigate the effect of strain rate on metal flow pattern in T-section extrusion process. Four different ram speeds were applied to realize how the shape and position of intermediate section would be affected. Flat-faced die with “T” final section was designed and manufactured. Straight layout of metal was of top concern in die design. Commercial purity aluminum, Al 99.5, was extruded in flat-faced die in hot condition. Graphite was used as lubricant in deformation process. After partial extrusion of billets, the residual part of billets pounced out of container and then mounted for metallographic tests. This part of billets consisted of dead-metal zone and deformation zone. Then, step-by-step decreasing of specimen height followed by macro-etching of metal surface paved the way for determining the metal flow pattern. An egg-shaped intermediate section appeared between initial round section and final “T” section. The size and position of the intermediate section changed by varying the strain rate of extrusion process; It was also revealed that as the strain rate of extrusion process is increased, the dead-metal zones become narrower and the dead-metal zone semi angle increases.

Dementia-friendly architecture: environments that facilitate wayfinding in nursing homes.

Spatial disorientation is a prime reason for institutionalization. The autonomy of the residents and their quality of life, however, is strongly linked with their ability to reach certain places within their nursing home. The physical environment has a great potential for supporting a resident's wayfinding abilities. For this study, data were collected from 30 German nursing homes. Skilled nurses rated the resident's ability to perform 5 wayfinding tasks. The architectural characteristics of the homes were analyzed and their impact on the resulting scores was tested for statistical significance using the Mann-Whitney U test (P < .05). Results confirm that people with advancing dementia are increasingly dependent on a compensating environment. The significant factors include a small number of residents per living area, the straight layout of the circulation system without any changes in direction, and the provision of only 1 living/dining room. These and additional results were transformed into architectural guidelines.

Water-to-water heat transfer in tube–tube heat exchanger: Experimental and analytical study

Tube–tube heat exchanger (TTHE) is a low cost, vented double wall heat exchanger which increases reliability by avoiding mixing of fluids exchanging heat. It can be potentially used for heat recovery from engine cooling circuit, oil cooling, desuperheating in refrigeration and air conditioning, dairy, and pharmaceutical industry, chemical industry, refinery, etc. These tube–tube heat exchangers are successfully demonstrated for superheat recovery water heating applications, condenser and evaporator in heat pumps, lube oil cooler for shipboard gas turbines, milk chilling and pasteurizing application. This paper presents an experimental study on various layouts of TTHE for water-to-water heat transfer. The theoretical and experimental results on this type of heat exchanger configuration could not be located in literature. Overall heat transfer coefficient and pumping power were experimentally determined for a fixed tube length and surface area of serpentine layouts with different number of bends and results are compared with straight tube TTHE. In the case investigated, serpentine layout TTHE with seven bends has shown optimum performance, with overall heat transfer coefficient 17% higher than straight tube TTHE. Two out of five serpentine layout TTHE have shown poor heat transfer performance than straight tube TTHE. The experimental results also indicate that there is a definite optimum for a number of bends in serpentine layout TTHE. An analytical model for prediction of thermo-hydraulic performance of straight layout has been developed and validated experimentally.

Chasma Australe, Mars: Structural Framework for a Catastrophic Outflow Origin

Chasma Australe, 500 km long and up to 80 km wide, is the most remarkable of the martian south pole erosional reentrants carved in the polar layered deposits. We have interpreted Chasma Australe erosional and depositional features as evidence for a flood origin, which we have reconstructed using a modified Manning equation. The main characteristics of the flow are a water velocity between 30 and 50 m s −1 and discharge values between 7 × 10 8 and 3 × 10 9 m 3 s −1, very near to MGS data-based estimations for martian outflow channels (D. E. Smith et al. 1998, Science 279, 1686–1692). We thus postulate that Chasma Australe originated in a catastrophic flood. The tectonic study of an area (roughly 20 million km 2 in size) around Mars' south pole included the measurement and projection in rose diagrams of more than 300 lineaments, of which 85 were wrinkle ridges and the rest straight scarps. The whole set of lineaments canbe explained by a stress field with a σ 1 N10°E in strike, the wrinkle ridges being reverse faults and the other lineaments direct and strike-slip faults. The straight layout of parts of Chasma Australe almost 200 km long suggests that the chasma was carved following a fracture network. The effectiveness of the erosional process (the canyon is up to 1000 m deep) leads us to suspect that this carving was preceded by a sapping period. Endogenetic and exogenetic processes would thus have contributed to the origin of this landform.

The Rocher de l’Escalade Viaduct, France

The 64 km long Maurienne Motorway currently under construction will complete a highway link between Lyon, France, and Turin, Italy via the Frejus Tunnel, which was opened in 1980. The Arc River flows through the Maurienne valley, along with an existing main road and railway line.The new motorway is at the bottom of the valley. The viaduct at Rocher de l’Escalade crosses the river, the road and the railway at a significant skew. It has four spans, 55 + 64 + 64 + 56 m, for a total length of 239 m, with two piers in the riverbed and one between the road and the railway embankment. This viaduct is representative of the bridges for this motorway, although its largely straight layout is less complicated than most others.

Effect of the shape of the transition section on head losses in intakes of a pumped-storage station

1. In intakes of the upper reservoirs of pumped-storage stations for straight variants and for layouts with bends (R=4dc) the coefficients of head losses in the pump operating regime are 2–3 times greater than in the turbine. 2. The experimental value of the coefficient of head losses ξplexy, taking into account losses in the intake proper and in the bend located behind it, in the pump regime, as a rule, differs substantially from the sum ξplexy=0+ξt.b.calc of the experimental value of the coefficient of losses of a straight intake and coefficient of head losses in the bend calculated by the recommendations given in the literature. This is due to the fact that the bend affects the value of losses in elements of the intake located above it. Therefore, a reliable value of the resistance coefficient of an intake with a bend in the pump regime can be obtained only experimentally. In the turbine operating regime the coefficients ξtlexy and ξtlexy=0+ ξt.b.calc for intakes with a bend differ among themselves by less than 12%. 3. Intakes with various degrees of expansion and transition section 2 from a circle to a rectangle (b=1.67dc, h=dc) located between the bend and intake proper have smaller head losses than intakes with transition section 1 from a circle to a square (b=h=dc) for all angles of turn of the bend (γ=0–90°) both in the pump and in the turbine regimes. 4. In intakes with transition section 1 (b=h=dc) in the pump regime the total losses, including also the losses in the bend, increase with increase of γ of the bend. In more extensive intakes with transition section 2 (b=1.67dc, h=dc) straight layouts (γ=0) have minimum losses; in the presence of a bend with γ=25° and γ=90° the coefficients of head losses are practically the same and, on average, are 45% greater than when γ=0, and when γ=60° are 4.5–10.5% less than when γ=25 and 90°. 5. In intakes with bends (R=4dc) of rectangular section (b=1.67dc, h=dc) with an area 2.12 times greater than the area of the conduit and transition 2 located between the conduit and bend, in the pump regime the coefficient of head losses are 1.4–1.5 times less than in intakes with bends of circular section (d=dc) for all investigated angles of turn of the bend. 6. In the turbine operating regime the total coefficients of head losses increase with increase of the angle of turn of the bend.