Design, fabrication and testing of sandwich coupled inductors

A planar coupled inductor having sandwich coil structure is fabricated using MEMS microfabrication techniques. The structure of the inductor coil is designed to achieve high coupling and high winding number with a relatively small coil area. In this work, the structure is fabricated by bonding two planar on-chip coil fabricated on two different substrates. This method can replace the conventional via connections that cause various problems in output pads interconnection. The functionality of the fabricated device was tested, while the basic characteristics of the fabricated coil were measured at wide range of operating frequency using cascade GSG probe and compared with the simulation. For measurements up to 1?GHz, three resonance frequencies, inductance of 35?nH and resistance of as low as 25?Ω were observed. The results show that the proposed technique is a promising alternative method for fabricating a simple and cost effective 3-D coupled inductors.     

北斗高精度定位的地质灾害监测系统的设计

针对滑坡等地质灾害实时监测难,传统的灾害监测方法自动化程度低、灾害预警不及时等问题,设计了基于北斗的地质灾害监测系统.该系统主要由数据采集终端、数据传输层和软件端三部分构成.数据采集终端集成了树莓派、北斗定位模块、雨量计、温湿度传感器、摄像头模块等,并通过数据传输层将实时地质数据传输至云端,实现了数据自动采集与传输.系...     

Relationship between mechanical properties and crystal structure in cocrystals and salt of paracetamol

Abstract

Objectives were to study mechanical properties of various solid forms of paracetamol and relate to their crystal structures. Paracetamol form I (PRA), its cocrystals with oxalic acid (PRA-OXA) and 4,4-bipyridine (PRA-BPY) and hydrochloride salt (PRA-HCL) were selected. Cocrystals and salt were scaled-up using rational crystallization methods. The resulting materials were subjected to different solid-state characterizations. The powders were sieved and 90–360?µm sieve fraction was considered. These powders were examined by scanning electron microscopy (SEM) and densities were determined. Tablets were made at applied pressures of 35–180?MPa under controlled conditions and the tablet height, diameter and hardness were measured. Tensile strength and porosity of the tablets were estimated using well known models. Crystal structures of these systems were visualized and slip planes were identified. Cocrystal and salt of PRA were physically pure. Sieved powders had comparable morphologies and particle size. The apparent and theoretical densities of powders were similar, but no clear trends were observed. The tensile strengths of these compacts were increased with increasing pressure whereas tabletability decreased in the order oxalic acid?>?PRA-HCL?≈?PRA-OXA?>?BPY?>?PRA-BPY. Tablet tensile strength decreases exponentially with increasing porosity with the exception of PRY-BPY and BPY. Slip plane prediction based on attachment energies may not be independently considered. However, it was possible to explain the improved mechanical properties of powders based on the crystal structure. Cocrystallization and salt formation have introduced structural features that are responsible for improved tableting properties of PRA.     

A simulation as a service cloud middleware

Many seemingly simple questions that individual users face in their daily lives may actually require substantial number of computing resources to identify the right answers. For example, a user may want to determine the right thermostat settings for different rooms of a house based on a tolerance range such that the energy consumption and costs can be maximally reduced while still offering comfortable temperatures in the house. Such answers can be determined through simulations. However, some simulation models as in this example are stochastic, which require the execution of a large number of simulation tasks and aggregation of results to ascertain if the outcomes lie within specified confidence intervals. Some other simulation models, such as the study of traffic conditions using simulations may need multiple instances to be executed for a number of different parameters. Cloud computing has opened up new avenues for individuals and organizations with limited resources to obtain answers to problems that hitherto required expensive and computationally-intensive resources. This paper presents SIMaaS, which is a cloud-based Simulation-as-a-Service to address these challenges. We demonstrate how lightweight solutions using Linux containers (e.g., Docker) are better suited to support such services instead of heavyweight hypervisor-based solutions, which are shown to incur substantial overhead in provisioning virtual machines on-demand. Empirical results validating our claims are presented in the context of two case studies.     

Analysis of nanofluid transport through a wavy channel

Laminar forced convection of heat transfer and pressure drop of Al₂O₃ and CuO/water nanofluids flow through a horizontal tube and wavy channel under constant wall temperature boundary condition is numerically investigated. Two different models were employed in our study: single phase (homogenous and dispersion) and two phase (Lagrangian–Eulerian model or discrete-phase model (DPM) and the mixture). The effects of various parameters, such as particle concentration, particle diameter, particle type, constant or temperature-dependent properties, wave amplitude, Reynolds number and Peclet number on the thermal, and flow field of the Nanofluids are analyzed. Our results revealed that variable properties assumption play a dominant role in horizontal tubes and provide better predictions for the heat transfer enhancement. The difference between constant and variable properties becomes insignificant and can be ignored in wavy channel due to the high mixing and generated recirculation zones, whereas the difference between the DPM and the single-phase variable properties diminish as Peclet number and volume fraction increases. However, dispersion model shows an excellent agreement with the experimental data; the absence of the reference values for the adjustable factor C_d in the open literature put it in a questionable position. Therefore, DPM and homogenous single-phase model with well-chosen thermal conductivity and viscosity correlations can be considered as an accurate way and more dependable in nanofluid simulations especially the homogenous single-phase model because it requires less time, CPU, and memory usage. As expected, it is found that the heat transfer increases as the Reynolds number and particle volume fraction increases, but it is accompanied by a higher pressure drop. The obtained results have been successfully validated and compared with the experimental and numerical data available in the literature.     

Estimation of optimum binder content of recycled asphalt incorporating a wax warm additive using response surface method

This paper presents a new approach to estimate the optimum binder content (OBC) of recycled asphalts (RAs) incorporating a warm mix additive based on the interaction effects of compaction temperature, RA content and binder content using volumetric and strength characterisation. The experimental design was developed using response surface method (RSM) based on central composite design for various compaction temperatures (130–160 °C), RA contents (30–50%) and binder contents (4.9–6.0%). Laboratory tests were performed and analysed to meet the desired volumetric and strength properties according to the Malaysian specifications for the design of dense asphalt mixtures. Statistical analysis and mathematical models proposed by RSM were used to determine the OBC. The results showed that compaction temperature is the most significant factor in determining the OBC. There are minimum differences in the OBC variation of samples incorporating different dosage of RA. The developed model can be used for quick estimation of OBC for various levels of compaction temperature and RA content.     

Effects of Pretreatment on Properties of Gelatin from Perch (Lates Niloticus) Skin

Fish gelatins obtained from perch fish skin pretreated with various solutions containing acetic acid, sodium hydroxide (NaOH) and sodium chloride (NaCl) were successfully characterized for their nanostructure pattern using field emission scanning electron microscopy. Each pretreatment transformed collagen to gelatin with fibril, zigzag cracks, straight rods, and cross-linked rods nanostructure patterns. Pretreatment solutions also affect the gel yield, gel strength, amino acid profile, and functional groups in perch gelatin as analyzed by Fourier transform infrared spectroscopy. Samples pretreated with NaCl, NaOH, and acetic acid solution showed the highest gel yield (22.84%) and gel strength (179.84 g). Fourier transform infrared spectra for perch gelatins also revealed weak C–N amide II and III bond stretches as well as weak C=O bond stretch.     

High-pressure steam curing of high-slag cement. II. Strength of cement-sand mixes

The strength of dense high-slag cement-sand mixes autoclaved at 180 lbf/in², and of certain aerated mixes autoclaved at pressures ranging from 120 to 210 lbf/in², has been determined. It was found that maximum strengths were developed in an autoclaving period of 5 h at 180 lbf/in², and that longer periods, as well as higher autoclaving pressures, yielded lower strengths. The maximum strength values obtained for compacted 1: 3 (w/w) mixes were 425 kg/cm² in the absence of fine quartz, and 510 kg/cm² in the presence of suitable addition of fine quartz. The corresponding values for Portland cement mixes were, respectively, 330 and 460 kg/cm² for a heating period of 5 h, and 360 and 505 kg/cm² for a period of 6 h.