Definable nilpotent and soluble envelopes in groups without the independence property

We prove that in a group without the independence property a nilpotent subgroup is always contained in a definable nilpotent subgroup of the same nilpotency class. The analogue for the soluble case is also shown when the subgroup is normal in the ambient group.     

Applicability of medium-size basis sets in calculations of molecular dynamic polarisabilities

Static and dynamic average polarisabilities and polarisability anisotropies of seven linear non-polar and polar molecules are calculated within the CCS, CC2, and CC3 approximations using a range of medium-sized basis sets: the polarised LPol-n (n = ds, dl, fs, fl), the aug-pc-n (n = 1, 2), the def2-SVPD, and -TZVPD basis sets. Reference values are obtained using a hierarchy of Dunning's (d-)aug-cc-pVXZ (X = D, T, Q, 5) basis sets. The results are discussed together with the available CCSD values in terms of basis set and correlation method errors, and their ratio. Detailed analysis shows that already the def2-SVPD basis set can be used in CCS polarisability calculations. When affordable, the slightly larger aug-pc-1 basis set is recommended, as it leads to significant reduction of basis set error. The def2-TZVPD, LPol-ds, and aug-pc-2 basis sets are optimal choice within the CC2 approximation, with the latter allowing to approach the CC2 basis set limit. The LPol-ds, -dl, and def2-TZVPD sets outperform the aug-cc-pVTZ set in average polarisability CCSD calculations, with the def2-TZVPD being competitive to other reduced-size sets also in determination of polarisability anisotropy. The aug-pc-2 basis is a particularly attractive choice for CCSD, giving the accuracy of aug-cc-pVQZ at a significantly reduced computational cost. The polarisability anisotropy is shown to be more computationally demanding than the average polarisability, in particular with respect to the accuracy of the correlation method and an accurate evaluation of this property requires at least the CCSD model.     

基于无线传感器网络的温室大棚温湿度监控系统研究

文章提出了一种基于CC2530和SHT75温湿度传感器的温湿度实时监控系统的实现方案。文中阐述了系统的总体设计,包括硬件设计以及软件设计方法。通过SHT75芯片对温湿度数据进行采集,并利用ZigBee技术对采集来的数据进行传输,实现了温室大棚温湿度的实时多点检测。     

基于ZigBee与安卓的智能远程监控系统的设计

随着中国经济与社会的快速发展,环境监测引起人们的广泛关注。为了解决目前监控系统的不足,设计一种基于ZigBee和因特网的智能远程监控系统。该系统采用TI公司的CC2530芯片及相应传感器构建ZigBee局域网,将采集到的温湿度信息,经过上位机存储并处理,利用因特网或无线移动网络,在安卓智能手机终端上实现数据的远程传输。通过上位机与手机终端,可以查看当前环境状态,保存历史数据,并进行自动报警。给出系统硬件及软件实现方法,包括节点设计、组网流程、数据传输功能、上位机软件设计、安卓智能手机终端软件设计等。实验测试结果说明该系统工作稳定、容易扩展、上位机及手机操作简便。     

基于ZigBee的煤层气录井红外甲烷监测系统设计

针对传统煤层气录井系统中采用老式传感器和有线网络对煤层气甲烷含量进行监测实时性差和精度不高等问题,该文设计一种红外甲烷技术和ZigBee无线传输技术相结合的新型煤层气甲烷监测系统。该系统以MSP430F449单片机和CC2430芯片为核心,采用ZigBee无线通信协议。其可实时采集传输甲烷含量数据,具有稳定性高,拓展能力强,精度高,实用性强等优点。     

Splitting families of sets in ZFC

Miller's 1937 splitting theorem was proved for every finite n>0$n>0$ for all ρ-uniform families of sets in which ρ is infinite. A simple method for proving Miller-type splitting theorems is presented here and an extension of Miller's theorem is proved in ZFC for every cardinal ν for all ρ  -uniform families in which ρ≥_?ω(ν)$\rho \ge {\mathrm{?}}_{\omega }(\nu )$. The main ingredient in the method is an asymptotic infinitary Löwenheim–Skolem theorem for anti-monotone set functions.     

Ugi three-component coupling reaction for the synthesis of 2-(6-oxo-11-phenyl-7,8-dihydrobenzo[b]pyrrolo[1,2-d][1,4]diazocin-5(6H)-yl)-2-phenylacetamide derivatives

A three-component, four center Ugi reaction of 3-(1-(2-aminophenyl)-5-phenyl-1H-pyrrol-2-yl)propanoic acid with aromatic aldehyde and t-butyl isocyanide has been achieved to produce a novel class of N-tert-butyl-2-(6-oxo-11-phenyl-7,8-dihydrobenzo[b]pyrrolo[1,2-d][1,4]diazacine-5(6H)-yl)-2-phenylacetamides in moderate to good yields.     

25FS管莫尔条纹的成因及对策

本文详细介绍了技术质量部对用户厂家反映我公司25FS管莫尔条纹的问题进行的深入探究,发现其产生的三大主要物理原因,并作了适当的数学说明,并提出了相应的对策.     

Impact of Coronavirus Pandemic Crisis on Technologies and Cloud Computing Applications

In light of the coronavirus disease 2019 (COVID-19) outbreak caused by the novel coronavirus, companies and institutions have instructed their employees to work from home as a precautionary measure to reduce the risk of contagion. Employees, however, have been exposed to different security risks because of working from home. Moreover, the rapid global spread of COVID-19 has increased the volume of data generated from various sources. Working from home depends mainly on cloud computing (CC) applications that help employees to efficiently accomplish their tasks. The cloud computing environment (CCE) is an unsung hero in the COVID-19 pandemic crisis. It consists of the fast-paced practices for services that reflect the trend of rapidly deployable applications for maintaining data. Despite the increase in the use of CC applications, there is an ongoing research challenge in the domains of CCE concerning data, guaranteeing security, and the availability of CC applications. This paper, to the best of our knowledge, is the first paper that thoroughly explains the impact of the COVID-19 pandemic on CCE. Additionally, this paper also highlights the security risks of working from home during the COVID-19 pandemic.