Study on micro-injection molding of light guiding plate by numerical simulation

Micro-injection molding is the most important technology in optical MEMS/NEMS industry for the necessary of scale, velocity and cost by the development of optical MEMS/NEMS industry and the innovation of optical MEMS/NEMS industry. It has the advantage of low cost, low interface and small volume in optical MEMS/NEMS industry. This paper emphasizes the analysis for light guiding plate of liquid crystal display on micro-injection molding. The finite element simulation in a three-dimensional inertia-free, incompressible flow is presented. A control volume scheme with a fixed finite element mesh is employed to predict melt front advancement. The plastic material of light guiding plate is used for PMMA material. The results show that the short shot situation on the filling stage of micro-injection molding. The results also indicate that the processing is very well for micro-injection molding by numerical simulation.     

Performance Evaluation of Reinforced Concrete Bridge Columns Wrapped with Fiber Reinforced Polymers

This study investigates the performance of new bridge columns wrapped with fiber reinforced polymers (FRP) when exposed to aggressive environmental conditions. This has been accomplished through field monitoring and laboratory tests. As part of the field monitoring, temperature data were collected at various locations of bridge columns. In addition, visual inspection of two bridges was performed periodically for over a period of two years. No evidence of deterioration of the FRP wraps was detected during that period. Laboratory tests were performed to investigate how FRP wraps protect reinforced concrete columns from corrosion, and freeze–thaw laboratory tests were conducted to study the impact of temperature cycles on the mechanical behavior of FRP-wrapped columns. From the corrosion experimental tests, it was found that FRP provides excellent protection against aggressive agents (salty water or moisture) even when a single layer is used. Compression tests were conducted on specimens subjected to freeze–thaw cycles. It was found that minor thermal cycles have no effect on the performance of FRP-wrapped concrete specimens. However, for large thermal cycles, some degradation of ductility in the axial and the hoop directions was observed.     

Vibration analysis of edge-cracked beam on elastic foundation with axial loading using the differential quadrature method

The eigenvalue problems of clamped-free and hinged-hinged Bernoulli-Euler beams on elastic foundation with a single edge crack, axial loading and excitation force were numerically formulated using the differential quadrature method (DQM). Appropriate boundary conditions accompanied the DQM to transform the partial differential equation of a Bernoulli-Euler beam with a single edge crack into a discrete eigenvalue problem. The DQM results for the natural frequencies of cracked beams agree well with other literature values. The sampling point number effect, the location of the crack effect and the depth of the crack effect on the accuracy variation of calculated natural frequencies are presented by using two elements in this work. The effects of axial loading, foundation stiffness, opening crack and closing crack are also studied.     

An algorithm for calculating the lower confidence bounds of CPU and CPL with application to low-drop-out linear regulators

In assessing the performance of normal stable manufacturing processes with one-sided specification limits, process capability indices C_PU and C_PL have been widely used to measure the process capability. The purpose of this paper is to develop an algorithm to compute the lower confidence bounds on C_PU and C_PL using the UMVUEs of C_PU and C_PL. The lower confidence bound presents a measure on the minimum capability of the process based on the sample data. We also provide tables for the engineers/practitioners to use in measuring their processes. A real-world example taken from a microelectronics device manufacturing process is investigated to illustrate the applicability of the algorithm. Implementation of the existing statistical theory for capability assessment fills the gap between the theoretical development and the in-plant applications.     

Thermal performance of plate-fin vapor chamber heat sinks

Since vapor chambers exhibit excellent thermal performance, they are suited to use as bases of heat sinks. This work experimentally studies the thermal performance of plate-fin vapor chamber heat sinks using infrared thermography. The effects of the width, height and number of fins and of the Reynolds number on the thermal performance are considered. Experimental data are compared with corresponding data for conventional aluminum heat sinks. The results show that generated heat is transferred more uniformly to the base plate by a vapor chamber heat sink than by a similar aluminum heat sink. Therefore, the maximum temperature is effectively reduced. The overall thermal resistance of the vapor chamber heat sink declines as the Reynolds number increases, but the strength of the effect falls. The effect of the fin dimensions on the thermal performance is stronger at a lower Reynolds number. At a low Reynolds number, a suitable number of fins must be chosen to ensure favorable thermal performance of the vapor chamber heat sink. However, at a high Reynolds number, the thermal performance improves as the fin number increases.     

Thermal-fluid characteristics of plate-fin heat sinks cooled by impingement jet

This work experimentally and numerically studies the thermal-fluid characteristics of plate-fin heat sinks under impingement cooling by adjusting the impinging Reynolds number, the impingement distance, and the fin dimensions. The parameters and the ranges under consideration are the impinging Reynolds number (Re = 5000–25,000), the impingement distance (Y/D = 4–28), the fin width (W/L = 0.08125–0.15625) and the fin height (H/L = 0.375–0.625). The results show that the heat transferred by the heat sink increases with the impinging Reynolds number. The thermal performance can be improved significantly even at low impinging Reynolds number. However, the improvement becomes indistinct as the impinging Reynolds number increases. The thermal resistance declines as the impingement distance increases, and is minimal at Y/D = 20 for various impinging Reynolds numbers. Additionally, the thermal resistance increases as the impingement distance increases further. Increasing the fin width can effectively reduce the thermal resistance. However, as the fin width increases beyond a particular value, the thermal resistance increases dramatically. Reducing the thermal resistance by increasing the fin height depends on a suitable impinging Reynolds number and fin width. Therefore, the effect of the fin height is weaker than that of the impinging Reynolds number or the fin width.     

Dendritic Pt shells coated on concave Pd nanocrystals: synthesis and use as electrocatalysts for acidic oxygen reduction reaction

A simple method to prepare a dendritic Pt-shell coating on concave Pd nanoparticles (NPs) was successfully developed. In this study, tuning the Pt precursor concentration in the reaction mixture allowed control over the length of the outer Pt dendrites, enclosed by (211) high-index facets or (110) facets were performed. The concave Pd NPs covered by short Pt dendrites (Pd/S-Pt) and long Pt dendrites (Pd/L-Pt) were applied as catalysts for the oxygen reduction reaction (ORR) in 0.1 M HClO₄ electrolyte solution. Pd/S-Pt with (211) facets had higher specific activity (0.106 mA cm^?2) than that of Pd/L-Pt with (110) facets (0.066 mA cm^?2) or commercial Pt/C (0.076 mA cm^?2). Additionally, the accelerated durability test (ADT) results revealed that the decay for the ORR kinetic current catalysed by Pd/S-Pt was 28.21%, which was smaller than that of Pt/C (58.15%). Thus, Pd/S-Pt was effective for catalysis of the ORR.     

Diffusion barrier properties of AlMoNbSiTaTiVZr high-entropy alloy layer between copper and silicon

The application of an AlMoNbSiTaTiVZr high-entropy alloy film as diffusion barrier for copper metallization has been investigated. The AlMoNbSiTaTiVZr and copper layers are deposited sequentially, without breaking vacuum, onto silicon substrates by DC magnetron sputtering. The AlMoNbSiTaTiVZr films are found to possess a stable amorphous structure due to their high-entropy and limited diffusion kinetics. The AlMoNbSiTaTiVZr high entropy alloy film is determined to prevent copper-silicide formation up to 700 °C for 30 min. Thus, HEAs appear to have potential use as effective diffusion barriers for copper metallization.     

Blocking and nonblocking multirate Clos switching networks

This paper investigates in detail the blocking and nonblocking behavior of multirate Clos switching networks at the connection/virtual connection level. The results are applicable to multirate circuit and fast-packet switching systems. Necessary and sufficient nonblocking conditions are derived analytically. Based on the results, an optimal bandwidth partitioning scheme is proposed to reduce switch complexity while maintaining the nonblocking property. The blocking behavior of blocking switches supporting multicast connections is investigated by means of simulation. We propose a novel simulation model that filters out external blocking events without distorting the bandwidth and fanout (for multicasting) distributions of connection requests. In this way, the internal blocking statistics that truly reflect the switch performance can be gathered and studied. Among many simulation results, we have shown that for point-to-multipoint connections, a heuristic routing policy that attempts to build a narrow multicast tree can have relatively low blocking probabilities compared with other routing policies. In addition, when small blocking probability can be tolerated, our results indicate that situations with many large-fanout connection requests do not necessarily require a switch architecture of higher complexity compared to that with only point-to-point requests     

Functionalized terfluorene for solution-processed high efficiency blue fluorescence OLED and electrophosphorescent devices

A new multifunctional blue-emitting terfluorene derivative (TFDPA) featured with triphenylamine groups for hole-transportation and long alkyl chains for solution processability on the conjugation inert bridge centers was reported. TFDPA can give homogeneous thin film by solution process and exhibits high hole mobility (μ_h ≈ 10^?3 cm² V^?1 s^?1) and suitable HOMO for hole injection. Particularly, TFDPA performs efficient deep-blue emission with high quantum yield (～100% in solution, 43% in thin film) and suitable triplet energy (E_T = 2.28 eV), making solution-processed OLED devices of using TFDPA as blue emitter and as host for iridium-containing phosphorescent dopants feasible. The solution-processed nondoped blue OLED device gives saturated deep-blue electroluminescence [CIE = (0.17, 0.07)] with EQE of 2.7%. TFDPA-hosted electrophosphorescent devices performed with EQE of 6.5% for yellow [(Bt)₂Ir(acac)], 9.3% of orange [Ir(2–phq)₃], and 6.9% of red [(Mpq)₂Ir(acac)], respectively. In addition, with careful control on the doping concentration of [(Bt)₂Ir(acac)], a solution-processed fluorescence–phosphorescence hybrided two-color-based WOLED with EQE of 3.6% and CIE coordinate of (0.38, 0.33) was successfully achieved.