Development and Integration of MEMS Based Inductive Sensors

Inductive sensors are one of the most widely used sensors especially in automotive. However, with the current PCB manufacture process, the large size of the sensor limits its usage in different applications. In this thesis, a novel method of fabricating bi-layer copper micro inductive sensor is demonstrated to solve the size issue. The two coil layers were built by UV LIGA process respectively, and a polyimide insulation film sandwiched in between. At the beginning, seeding layer was deposited on the substrate as electrode, and then the copper coil layer was created through electroplating in the patterned micromold. The coil was prepared after striping off the seeding layer and micromold. Lately, the fabricated coil chips, ASIC, and capacitors were integrated together through PCB board by using wire bonding and SMT process. A reliable procedure of building robust micro inductive sensor was developed with the consideration of future mass production possibility. The good test results compared with simulation proved the feasibility of developing and fabricating miniaturized micro inductive sensor

FedRolex: Model-Heterogeneous Federated Learning with Rolling Sub-Model Extraction

Most cross-device federated learning (FL) studies focus on the model-homogeneous setting where the global server model and local client models are identical. However, such constraint not only excludes low-end clients who would otherwise make unique contributions to model training but also restrains clients from training large models due to on-device resource bottlenecks. In this work, we propose FedRolex, a partial training (PT)-based approach that enables model-heterogeneous FL and can train a global server model larger than the largest client model. At its core, FedRolex employs a rolling sub-model extraction scheme that allows different parts of the global server model to be evenly trained, which mitigates the client drift induced by the inconsistency between individual client models and server model architectures. We show that FedRolex outperforms state-of-the-art PT-based model-heterogeneous FL methods (e.g. Federated Dropout) and reduces the gap between model-heterogeneous and model-homogeneous FL, especially under the large-model large-dataset regime. In addition, we provide theoretical statistical analysis on its advantage over Federated Dropout and evaluate FedRolex on an emulated real-world device distribution to show that FedRolex can enhance the inclusiveness of FL and boost the performance of low-end devices that would otherwise not benefit from FL. Our code is available at: https://github.com/AIoT-MLSys-Lab/FedRolexComment: 20 pages, 7 Figures, Published in 36th Conference on Neural Information Processing And System

Third-order intrinsic anomalous Hall effect with generalized semiclassical theory

The linear intrinsic anomalous Hall effect (IAHE) and second-order IAHE have been intensively investigated in time-reversal broken systems. However, as one of the important members of the nonlinear Hall family, the investigation of third-order IAHE remains absent due to the lack of an appropriate theoretical approach, although the third-order extrinsic AHE has been studied within the framework of first- and second-order semiclassical theory. Herein, we generalize the semiclassical theory for Bloch electrons under the uniform electric field up to the third-order using wavepacket method and based on which we predict that the third-order IAHE can also occur in time-reversal broken systems. Same as the second-order IAHE, we find the band geometric quantity, the second-order field-dependent Berry curvature arising from the second-order field-induced positional shift, plays a pivotal role to observe this effect. Moreover, with symmetry analysis, we find that the third-order IAHE, as the leading contribution, is supported by 15 time-reversal broken 3D magnetic point groups (MPGs), corresponding to a wide class of antiferromagnetic (AFM) materials. Guided by the symmetry arguments, a two-band model is chosen to demonstrate the generalized theory. Furthermore, the generalized third-order semiclassical theory depends only on the properties of Bloch bands, implying that it can also be employed to explore the IAHE in realistic AFM materials, by combining with first-principles calculations.Comment: 1 figur

Optimizing the thermal performance of building envelopes for energy saving in underground office buildings in various climates of China

This article investigates the influence of the thermal performance of building envelopes on annual energy consumption in a ground-buried office building by means of the dynamic building energy simulation, aiming at offering reasonable guidelines for the energy efficient design of envelopes for underground office buildings in China. In this study, the accuracy of dealing with the thermal process for underground buildings by using the Designer's Energy Simulation Tool (DeST) is validated by measured data. The analyzed results show that the annual energy consumptions for this type of buildings vary significantly, and it is based on the value of the overall heat transfer coefficient (U-value) of the envelopes. Thus, it is necessary to optimize the U-value for underground buildings located in various climatic zones in China. With respect to the roof, an improvement in its thermal performance is significantly beneficial to the underground office building in terms of annual energy demand. With respect to the external walls, the optimized U-values completely change with the distribution of the climate zones. The recommended optimal values for various climate zones of China are also specified as design references for public office building in underground in terms of the building energy efficiency

Two-dimensional Massless Dirac Fermions in Antiferromagnetic AFe2As2 (A = Ba, Sr)

We report infrared studies of AFe$_{2}$As$_{2}$ (A = Ba, Sr), two representative parent compounds of iron-arsenide superconductors, at magnetic fields (B) up to 17.5 T. Optical transitions between Landau levels (LLs) were observed in the antiferromagnetic states of these two parent compounds. Our observation of a $\sqrt{B}$ dependence of the LL transition energies, the zero-energy intercepts at B = 0 T under the linear extrapolations of the transition energies and the energy ratio ($\sim$ 2.4) between the observed LL transitions, combined with the linear band dispersions in two-dimensional (2D) momentum space obtained by theoretical calculations, demonstrates the existence of massless Dirac fermions in antiferromagnetic BaFe$_{2}$As$_{2}$. More importantly, the observed dominance of the zeroth-LL-related absorption features and the calculated bands with extremely weak dispersions along the momentum direction $k_{z}$ indicate that massless Dirac fermions in BaFe$_{2}$As$_{2}$ are 2D. Furthermore, we find that the total substitution of the barium atoms in BaFe$_{2}$As$_{2}$ by strontium atoms not only maintains 2D massless Dirac fermions in this system, but also enhances their Fermi velocity, which supports that the Dirac points in iron-arsenide parent compounds are topologically protected.Comment: Magneto-infrared study, Landau level spectroscopy, DFT+DMFT calculation

Construction of resilient S-boxes with higher-dimensional vectorial outputs and strictly almost optimal nonlinearity

Resilient substitution boxes (S-boxes) with high nonlinearity are important cryptographic primitives in the design of certain encryption algorithms. There are several trade-offs between the most important cryptographic parameters and their simultaneous optimization is regarded as a difficult task. In this paper we provide a construction technique to obtain resilient S-boxes with so-called strictly almost optimal (SAO) nonlinearity for a larger number of output bits $m$ than previously known. This is the first time that the nonlinearity bound $2^{n-1}-2^{n/2}$ of resilient $(n,m)$ S-boxes, where $n$ and $m$ denote the number of the input and output bits respectively, has been exceeded for $m>\lfloor\frac{n}{4}\rfloor$. Thus, resilient S-boxes with extremely high nonlinearity and a larger output space compared to other design methods have been obtained

Finite-element analysis method to ensure the safety of invisible capping beams reinforced via the quick-replacement method

This paper presents a Finite-Element Analysis (FEA) method to solve the problem of reduced bridge safety due toinsufficient durability of invisible capping beams. To reinforce a C30 invisible capping beam effectively and reasonably, aquick-repair replacement concrete reinforcement method was utilized, and the strength necessary for the appropriate admixtureassessed. Specifically, the bearing capacity of the reinforced capping beam was studied via a single-point loading test, and theoptimal replacement thickness required to install the beam within two days and restore normal operation within three days wasdetermined using the non-linear software package MIDAS FEA. A finite-element model of equivalent size was employed usingMIDAS FEA to obtain the deflection, tensile stress, and pressure stress at the boundary. The results indicate that C40 earlystrength concrete with 0.1–0.2% sodium gluconate admixture has the appropriate properties to achieve the target. It can be usedto replace deteriorated concrete on the surface of invisible capping beams with a replacement rate of 30%. Further, to achievethe goal of resuming traffic within three days, the analysis results indicate that bilateral replacement with thickness 2 × 10 cm isoptimal and the maximum replacement thickness should not exceed 2 × 20 cm

Liquid-phase Hydrogenation of Phenol to Cyclohexanone over Supported Palladium Catalysts

The ZSM-5, g-Al2O3, SiO2 and MgO supported Pd-catalysts were prepared for the phenol hydrogenation to cyclohexanone in liquid-phase. The natures of these catalysts were characterized by XRD, N2 adsorption-desorption analysis, H2-TPR, CO2-TPD and NH3-TPD. The catalytic performance of the supported Pd-catalyst for phenol hydrogenation to cyclohexanone is closely related to nature of the support and the size of Pd nanoparticles. The Pd/MgO catalyst which possesses higher basicity shows higher cyclohexanone selectivity, but lower phenol conversion owing to the lower specific surface area. The Pd/SiO2 catalyst prepared by precipitation gives higher cyclohexanone selectivity and phenol conversion, due to the moderate amount of Lewis acidic sites, and the smaller size and higher dispersion of Pd nanoparticles on the surface. Under the reaction temperature of 135 oC and H2 pressure of 1 MPa, after reacting for 3.5 h, the phenol conversion of 71.62% and the cyclohexanone selectivity of 90.77% can be obtained over 0.5 wt% Pd/SiO2 catalyst. Copyright © 2016 BCREC GROUP. All rights reservedReceived: 7th March 2016; Revised: 13rd May 2016; Accepted: 7th June 2016How to Cite: Fan, L., Zhang, L., Shen, Y., Liu, D., Wahab, N., Hasan, M.M. (2016). Liquid-phase Hydrogenation of Phenol to Cyclohexanone over Supported Palladium Catalysts. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (3): 354-362 (doi: 10.9767/bcrec.11.3.575.354-362)Permalink/DOI: http://doi.org/10.9767/bcrec.11.3.575.354-36