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As IC components become denser and smaller in a package, more problems emerge. In the mold filling process, because epoxy molding compound (EMC) contains approximately 80 wt.% silica fillers, the fillers may clog at the gate of gap if the gap height between the component and the substrate is too small. This clogging will cause a popcorn effect due to the high resin content in the gap. In order to determine the EMC filling process in the mold cavity and the relation between the gap height and the filler size, we simulate the EMC filling process and the EMC filler concentration distribution in the mold cavity using mold flow analysis software and then use computational fluid dynamics-discrete element method (CFD-DEM) coupling method to simulate the EMC filler motion to determine the relationship between gap height and filler size and the factors that affect filler clogging. Based on the mold flow analysis results, the filler concentration was higher at the gate of gap than in other regions, and the filler concentration at the gate of gap for the 30- $\mu \text{m}$ gap-height model was higher than that for the 50- $\mu \text{m}$ gap-height model. Based on the DEM-CFD coupling results, particles with a single diameter larger than one-half of the gap height caused particle clogging the gate of gap, and particles with a mean particle size larger than one-third of the gap height caused particle clogging the gate of gap. [ABSTRACT FROM AUTHOR]

Pure shift techniques, as one of the rapidly developing frontiers in nuclear magnetic resonance (NMR) fields, can significantly enhance the resolution of NMR spectrum with a removal of splittings induced by scalar couplings. However, periodic artifacts due to residual scalar couplings during acquisition arise on all direct pure shift spectra, causing severe problems in analysis of complicated samples. Herein, we construct a signal model for the pure shift data and discuss the mechanism of periodic artifacts. Then, based on constraints on the low-rank property of pure shift NMR data, a subsequent artifact-suppression method is proposed to reconstruct a clean pure shift spectrum. With the proposed method, clean $^{\mathbf {1}}\text{H}$ pure shift spectrum can be obtained from only one experiment, greatly accelerating the experiment time while remaining the accuracy of the quantitative measurement. Experiments on a synthesis NMR signal, a complex sample of quinine with pseudo 2-D acquisition, and a medicine sample of azithromycin with 1-D acquisition are carried out to evaluate the feasibility and universality of the proposed method for different experimental techniques. Both the theoretical analysis and experimental results demonstrate the effectiveness of the proposed method for periodic artifacts suppression on complex samples and its potential for practical applications. [ABSTRACT FROM AUTHOR]

The control of heating, ventilation, and air-conditioning (HVAC) systems has raised extensive attention due to their high energy consumption cost and operation patterns far from being energy-efficient. However, most of the existing methods suffer limitations in scalability and computational efficiency for large buildings due to the centralized structures. To compensate for such defects, this article studies the scalable control of multizone HVAC systems with the target to reduce energy cost while maintaining thermal comfort. In particular, the thermal couplings due to heat transfer among the adjacent zones are incorporated, which has been ignored or not well studied due to complexity in the literature. To overcome the computational challenges of the nonlinear and nonconvex problem caused by the complex system dynamics, this article proposes a decentralized approach composed of three main steps: 1) relaxing the bilinear system dynamics; 2) solving the relaxed problem in a decentralized manner using the accelerated distributed augmented Lagrangian (ADAL) method; and 3) recovering the recursive feasibility of the solution. Through a comparison with the centralized method, the suboptimality of this approach is demonstrated. In addition, the superior performance of this approach is illustrated through a comparison with the distributed token-based scheduling strategy (DTBSS). The numerical results imply that for buildings with a relatively small number of zones (less than 20), the two methods are competitive. However, for larger cases, the proposed approach performs better with a considerable reduction both in energy cost and computation time. Note to Practitioners—This article develops a scalable computing framework for multizone HVAC controller, which can help reduce the electricity cost while maintaining the comfortable temperature bands set by the occupants. The proposed computing paradigm is scalable to large buildings as it mainly requires local zone-level computation. Specifically, for multizone buildings with a central shared HVAC system, the zone controllers determine the operations of their local variable air volume (VAV) boxes mainly through local computation and some necessary communications with the other entities. Consequently, this control technique can be implemented via local controllers deployed on simple hardware while applied to large buildings. The performance (electricity cost and computation time) of the controller is validated through a comparison with the centralized method and the DTBSS by using simulations. [ABSTRACT FROM AUTHOR]

Recently optical amplification technologies for mode-division multiplexing (MDM) transmission systems and networks have attracted great interest. In this article, we first propose a compact structure of few-mode Erbium-doped fiber amplifier (FM-EDFA) for weakly-coupled MDM amplification, which is characterized by weakly-coupled few-mode Erbium-doped fiber (EDF), cascaded mode-selective couplers (MSCs) for spatial mode control of pump lights, and few-mode wavelength multiplexer (FM-WMUX) for pump/signal coupling. Compared to previous studies, the proposed FM-EDFA has a similar structure with commercial single-mode EDFA (SM-EDFA) and can support weakly-coupled MDM transmission without inducing large modal crosstalk. Then related components are designed and fabricated for a 2-mode proposed FM-EDFA. The mode-field mismatching between transmission FMF and EDF under central alignment is investigated by simulation. Thanks to the effective suppression of modal crosstalk for the optical components, the transmission FMF, the EDF and their coupling, we experimentally demonstrate the first weakly-coupled MDM-WDM amplification and transmission over 15-km 2-mode FMF with 10-Gb/s optical on-off keying (OOK) modulation and direct detection. The proposed FM-EDFA can be extended to MDM transmission systems and networks supporting more modes. [ABSTRACT FROM AUTHOR]

Fano-like lineshapes in whispering-gallery modes (WGMs) microresonators are of critical for many actual applications, such as high-sensitivity sensors, slow light, and optical switches. In this paper, we theoretically and experimentally demonstrate dynamic transmission lineshapes, including Lorentzian lineshapes, Fano-like lineshapes and gain-like lineshapes, with a simple system, where a surface nanoscale axial photonic (SNAP) microbottle is coupled to the transition of a tapered fiber by carefully choosing tapered fiber diameters. Controlled and robust coupling with a clean and almost equidistant spectrum for different axial modes is achieved while maintaining contact between the resonator and the taper. Our device offers five similar dynamic transmission lineshapes arranged in order simultaneously, demonstrating stable tuning and a high number of potential degrees of freedom in contrast to other coupling systems for single- or double-coupled microresonators. By using coupled-mode theory, these transmission lineshapes are fitted to explain these experiment observations. We also explore a tunable transmission spectra obtained by increasing the powers of the input laser. Our approach hold unique potential in sensitivity-enhanced sensing, quantum information processing, and all-optical switching. [ABSTRACT FROM AUTHOR]

This paper presents the design of dual circularly polarized (CP) series-fed arrays based on the sequential rotation (SR) technique with uniform radiation elements. The radiation elements and feeding network used in the array are uniform, which leads to the possibility of dual-CP radiation by series-fed SR arrays. Meanwhile, the elements radiate unequal powers due to this arrangement. The relationship between the axial ratio and four key parameters of the array is derived and thoroughly discussed. Good polarization purity and port isolation can be realized by optimizing these parameters. A dual-CP array working at 10 GHz is designed with the help of the analysis. The experimental results show that the proposed antenna has good properties. [ABSTRACT FROM AUTHOR]

In this paper, the relationship between the magnetic properties and microstructures of nanocomposite isotropic exchange-coupled systems with the structure of \alpha -Fe crystalline grains embedded in Nd2Fe14B matrices has been estimated by micromagnetic finite-element method. And then, the results have been analyzed by means of the effectiveness of exchange coupling between the magnetically hard Nd2Fe14B and soft \alpha -Fe phase of the exchange-coupled Nd2Fe 14\text{B}/\alpha -Fe magnetic systems. The effectiveness of interphase exchange coupling has been estimated by the volume fractions of exchange coupling area near phase boundaries between \alpha -Fe grains and Nd2Fe14B matrix. The results have shown the micromagnetic mechanism of the advanced magnetic properties of the exchange coupled magnetic systems with the structure of $\alpha $ -Fe grains embedded in Nd2Fe14B matrix. In addition, the optimal magnetic properties can be expected in the case of comparatively the large grain sizes of $\alpha $ -Fe and Nd2Fe14B phase due to the characteristic structure of those magnetic systems. [ABSTRACT FROM AUTHOR]

We design and fabricate a corrugated grating on a polymer waveguide for the realization of the conversion between the fundamental mode and the higher order mode. The transmission characteristics of the device are insensitive to the polarization state of the input light. Our typical fabricated device shows a mode conversion efficiency higher than 99% over a bandwidth of $\sim 4$ nm and a temperature sensitivity of 3.5 nm/°C, which allows the operation wavelength of the device to be tuned over the $C+L$ band with a temperature control <30°C. This mode converter could be integrated with other waveguide devices to realize more sophisticated functions for mode-division-multiplexing systems. [ABSTRACT FROM PUBLISHER]