GQFedWAvg: Optimization-Based Quantized Federated Learning in General Edge Computing Systems

The optimal implementation of federated learning (FL) in practical edge computing systems has been an outstanding problem. In this paper, we propose an optimization-based quantized FL algorithm, which can appropriately fit a general edge computing system with uniform or nonuniform computing and communication resources at the workers. Specifically, we first present a new random quantization scheme and analyze its properties. Then, we propose a general quantized FL algorithm, namely GQFedWAvg. Specifically, GQFedWAvg applies the proposed quantization scheme to quantize wisely chosen model update-related vectors and adopts a generalized mini-batch stochastic gradient descent (SGD) method with the weighted average local model updates in global model aggregation. Besides, GQFedWAvg has several adjustable algorithm parameters to flexibly adapt to the computing and communication resources at the server and workers. We also analyze the convergence of GQFedWAvg. Next, we optimize the algorithm parameters of GQFedWAvg to minimize the convergence error under the time and energy constraints. We successfully tackle the challenging non-convex problem using general inner approximation (GIA) and multiple delicate tricks. Finally, we interpret GQFedWAvg's function principle and show its considerable gains over existing FL algorithms using numerical results.Comment: submitted to IEEE Transactions on Wireless Communications, under major revisio

Optimal multiple antenna design for compact MIMO terminals with ground plane excitation

The compactness of mobile terminals complicates the design of multiple antennas, since coupling among the antennas increases when they are placed in proximity of one another. While it is possible to mitigate coupling between closely spaced antennas, a tradeoff in bandwidth is required. In this paper, we highlight ground plane excitation as an additional dimension to consider in the design of multiple antenna terminals. This is because a compact ground plane, especially in mobile application, can interact with the antenna elements and contribute significantly to their radiation characteristics. Our results show that several design parameters, namely element locations, spacing between elements, and radiation characteristics of individual elements, must be jointly considered in order to achieve the optimal MIMO performance tradeoff for compact multiple antenna terminals

Decoupling of multiple antennas in terminals with chassis excitation using polarization diversity, angle diversity and current control

Excitation of the chassis enables single-antenna terminals to achieve good bandwidth and radiation performance, due to the entire chassis being utilized as the main radiator. In contrast, the same chassis excitation phenomenon complicates the design of multiple antennas for MIMO applications, since the same characteristic mode of the chassis may be effectively excited by more than one antenna, leading to strong mutual coupling and severe MIMO performance degradation. In this paper, we introduce a design concept for MIMO antennas to mitigate the chassis-induced mutual coupling, which is especially relevant for frequency bands below 1 GHz. We illustrate the design concept on a dual-antenna terminal at 0.93 GHz, where a folded monopole at one chassis edge excites the chassis’ fundamental electric dipole mode and a coupled loop at the other chassis edge excites its own fundamental magnetic dipole mode. Since the two radiation modes are nearly orthogonal to each other, an isolation of over 30 dB is achieved. Moreover, we show that the antenna system can be conveniently modified for multiband operation, such as in the 900/1800/2600 MHz bands. Furthermore, by controlling the phase of the feed current on the folded monopole, the two antennas can be co-located on the same chassis edge with an isolation of over 20 dB. The co-located dual antenna prototype was fabricated and verified in the measurements

Large screen enabled tri-port MIMO handset antenna for low LTE bands

In recent years, the screen-to-body ratio of mobile handsets has been increasing. Today, the screen nearly fills up the entire front side. Conventionally, the screen is mainly seen as a metallic object that adversely affects antenna performance. In this paper, the large screen is used for the first time to facilitate an additional uncorrelated MIMO port in a tri-port design, for several LTE bands below 1 GHz. To this end, the screen and the terminal chassis are modeled as two metal plates and their characteristic modes are analyzed. Four modes are then tuned to resonance and selectively excited to yield three uncorrelated MIMO ports. Simulation and measurement results are in good agreement. The measured bandwidths are 23%, 17% and 21%. Within the operating band, the measured isolation is above 13 dB, envelope correlation coefficient below 0.16 and average total efficiency above 72%

Impact of current localization on the performance of compact MIMO antennas

In this paper, we study the influence of current localization on the isolation between two antennas in a compact terminal setting. The two antennas are chosen to be a monopole and a PIFA. The degree of current localization is controlled by the permittivity value of the PIFA’s dielectric loading. Both lossless and lossy cases are simulated in order to ascertain the underlying performance impact from current localization and its potential use in real implementation. Our results show that significant isolation enhancement is achieved with more localized currents. Moreover, the technique improves the terminal’s diversity and capacity performance both at the center frequency and over a given bandwidth. In addition, PIFAs with dielectric loadings of higher permittivity values and more localized currents are physically smaller. Antenna prototypes are fabricated, and the measured results agree well with the simulated results

Characteristic mode based tradeoff analysis of antenna-chassis interactions for multiple antenna terminals

The design of multiple antennas in compact mobile terminals is a significant challenge, due to both practical and fundamental design tradeoffs. In this paper, fundamental antenna design tradeoffs of multiple antenna terminals are presented in the framework of characteristic mode analysis. In particular, interactions between the antenna elements and the characteristic modes and their impact on design tradeoffs are investigated in both theory and simulations. The results reveal that the characteristic modes play an important role in determining the optimal placement of antennas for low mutual coupling. Moreover, the ability of antenna elements to localize the excitation currents on the chassis can significantly influence the final performance. To demonstrate the effectiveness of the proposed approach, a dual-band, dual-antenna terminal is designed to provide an isolation of over 10 dB for the 900 MHz band without additional matching or decoupling structures. A tradeoff analysis of bandwidth, efficiency, effective diversity gain and capacity is performed over different antenna locations. Finally, three fabricated prototypes verify the simulation results for representative cases

Antagonistic effects of Lactobacillus plantarum 0612 on the adhesion of selected foodborne enteropathogens in various colonic environments

The study aims to investigate the antagonistic ability of Lactobacillus plantarum0612 against foodborne enteropathogens adhesion to the human intestinal Caco-2 cells by competition in a simulated colon model. L. plantarum0612 has been subjected to the gastrointestinal transits simulation (GITS) prior to assess its competitive inhibition on the adhesion of selected pathogenic strains using intestinal epithelial cells with different colonic pH conditions. Results showed that the adhesion of E. coli and L. monocytogenes on Caco-2 cells was significantly inhibited by L. plantarum0612 with 4.35 and 4.14 log reductions, respectively. Exclusion and competition mechanisms seemed to be more effective in pre-venting the colonization of pathogens, indicating L. plantarum0612 is able to compete for receptors of the epithelial cell surfaces. The GITS tolerance L. plantarum 0612 exhibited stronger competitive inhibition (p<0.05) on the adhesion of tested pathogens to the Caco-2 cells at lower colonic pH. It was observed that the viable count of E. coli significantly reduced by 5.10 log CFU/ml after 8 h of exposure at colonic pH 5.0. The antagonisms against the adhesion of all selected foodborne enteropathogens in the colonic conditions are probably due to the presence of surface adhesion proteins, which needs further investigation. However, the antagonistic effect of L. plantarum0612 indicates it could be a promising therapeutic approach for the prevention and management of foodborne diseases

Telecom InP/InGaAs nanolaser array directly grown on (001) silicon-on-insulator

A compact, efficient, and monolithically grown III–V laser source provides an attractive alternative to bonding off-chip lasers for Si photonics research. Although recent demonstrations of microlasers on (001) Si wafers using thick metamorphic buffers are encouraging, scaling down the laser footprint to nanoscale and operating the nanolasers at telecom wavelengths remain significant challenges. Here, we report a monolithically integrated in-plane InP/InGaAs nanolaser array on (001) silicon-on-insulator (SOI) platforms with emission wavelengths covering the entire C band (1.55 μm). Multiple InGaAs quantum wells are embedded in high-quality InP nanoridges by selective-area growth on patterned (001) SOI. Combined with air-cladded InP/Si optical cavities, room-temperature operation at multiple telecom bands is obtained by defining different cavity lengths with lithography. The demonstration of telecom-wavelength monolithic nanolasers on (001) SOI platforms presents an important step towards fully integrated Si photonics circuits

Habitual Sleep Quality Moderated the Effects of Sleep Deprivation on EmotionRegulation by Third-Person Self Talk: Event-Related Potential (ERP) andBehavioral Findings

The current study investigated the impact of sleep deprivation (SD) on the use of third-person self-talk, a relatively effort-less strategy, to regulate emotion. Twenty-four participants (age = 22.75 2.68, 54.17% male, 33.33% good sleepers) com-pleted a cue-picture ERP paradigm after normal sleep and SD conditions, in which they viewed negative or neutral stimuliand reflected on their feelings using either the pronoun I or their name (third-person). We calculated post-instruction latepositive potential (LPP) that has been found sensitive to emotion regulation strategies and closely related to amygdalaactivity. While poor sleepers showed greater LPP amplitudes overall, F(1,7) = 17.50, p = .004, SD only increased the LPPfor negative picture trials among good sleepers but not poor sleepers, F(1,7) = 5.37, p = .054, suggesting that the effect ofSD on emotion regulation using third-person self talk was moderated by habitual sleep quality

Monte Carlo simulations of the HP model (the "Ising model" of protein folding)

Using Wang-Landau sampling with suitable Monte Carlo trial moves (pull moves and bond-rebridging moves combined) we have determined the density of states and thermodynamic properties for a short sequence of the HP protein model. For free chains these proteins are known to first undergo a collapse "transition" to a globule state followed by a second "transition" into a native state. When placed in the proximity of an attractive surface, there is a competition between surface adsorption and folding that leads to an intriguing sequence of "transitions". These transitions depend upon the relative interaction strengths and are largely inaccessible to "standard" Monte Carlo methods.Comment: 6 pages, 6 figures. Article in press. To be published in Computer Physics Communications (2011