Milk Replacer Acidification for Free-Access Feeding: Effects on the Performance and Health of Veal Calves

Objectives of this study were to investigate the effects of milk replacer (MR) acidification for free- access feeding on pre- and post-weaning performance, morbidity and mortality of calves. Calves were randomly assigned to free-access feeding of acidified (ACID, n = 31) or non-acidified (NON, n = 31) MR, and weaned at 42 days. ACIDMR was prepared to pH 4.0 - 4.5 using formic acid. Intakes were measured daily and weights weekly. Samples of ACID and NON MR were analyzed for coliform and aerobic bacterial growth. After weaning, calves transitioned to a grain-fed veal diet, weighed every 2 weeks. At slaughter (approximately 6 months of age), lungs were evaluated for gross pathological changes and dressed carcass weights were obtained. Generalized linear mixed models were constructed to examine the effects of MR acidification. Differences by treatment group for pre- and post-weaning morbidity and mortality were tested using Pearson’s χ2 and Fisher’s exact tests. ACID calves consumed less MR than NON (10.6 vs. 11.7 L/d, P = 0.02). Acidification tended to promote earlier onset of starter ration consumption (32.0 vs. 39.5 d, hazard ratio = 1.5, P = 0.07), but did not affect average daily starter ration or water intakes across the pre-weaning period. ACID and NON calves did not differ for BW at weaning, pre- or post-weaning ADG or dressed carcass weight. ACID MR had less coliform (P < 0.001) and aerobic bacterial growth (P < 0.001) than NON MR, but odds of disease treatment and mortality did not differ. ACID calves tended to have lower odds of pulmonary lesions during post-mortem inspection than NON calves (OR = 0.3, P = 0.07). These results indicate that under free-access feeding conditions, acidification limited bacterial growth and MR intake, but there were no long-term impacts of acidification on calf performance or health. In conclusion, acidification to pH 4.0 - 4.5 will significantly reduce bacterial growth in milk fed to calves.

Uplink Grant-Free Pattern Division Multiple Access (GF-PDMA) for 5G Radio Access

Massive machine type communication(m MTC) is one of the key application scenarios for the fifth generation mobile communication(5 G). Grant-free(GF) transmission can reduce the high signaling overhead in m MTC. Non-orthogonal multiple access(NMA) can support more users for m MTC than orthogonal frequency division multiple access(OFDMA). Applying GF transmission in NMA system becomes an active topic recently. The in-depth study on applying GF transmission in pattern division multiple access(PDMA), a competitive candidate scheme of NMA, is investigated in this paper. The definition, latency and allocation of resource and transmission mechanism for GF-PDMA are discussed in detail. The link-level and system-level evaluations are provided to verify the analysis. The analysis and simulation results demonstrate that the proposed GF-PDMA has lower latency than grant based PDMA(GB-PDMA), possesses strong scalability to confront collision and provides almost 2.15 times gain over GF-OFDMA in terms of supporting the number of active users in the system.

Predicting octanol/water partition coefficient using solvation free energy and solvent-accessible surface area

The regression model for octanol/water partition coefficients ( K ow ), is founded with only two molecular descriptors available through quantum chemical calculations: solvation free energy (Δ G S ), and solvent accessible surface area (SASA). For the properties of 47 organic compounds from 17 types, the model gives a correction coefficient (adjusted for degrees of freedom) of 0 959 and a standard error of 0 277 log unit. It is a suitable way to predict the partition properties that are related to solute solvent interactions in the water phase.

DP-DQPSK Optical Access System Integrated with Fiber and Free-Space Downlink for High Spectral Efficiency Application

In this letter, we present the generation, the balanced detection, and the transmission performance evaluation of dual polarization differential quadrature phase shift keying (DP-DQPSK) signals in optical access system integrated with fiber and free-space downlink. Polarization-multip- lexed (POLMUX) technique is introduced in the system for high spectral efficiency access utilization. 10 Gb/s DP-DQPSK downlink signals are successfully transmitted over 50 km SMF-28 and a 800 m wireless optical channel under the bad weather condition, such as fog and haze. The results show that the potentiality of DP-DQPSK optical access system is integrated with fiber and free- space downlink for providing flexible user access with high bandwidth efficiency.

无蜂窝大规模MIMO系统接入点动态选择算法

在无蜂窝大规模多输入多输出(Multiple-Input Multiple-Output,MIMO)系统中,所有接入点(Access Point,AP)为用户提供服务的方式会造成较大的功率消耗和增加前传链路压力。以“用户为中心”的AP选择方案为每个用户选择最佳的AP集合,使系统频谱效率和能量效率得以提升。为了给每个用户选择最佳的AP集合,提出了一种基于反向传播(Back Propagation,BP)神经网络的接入点动态选择算法。将AP与用户之间的大尺度衰落向量作为输入,AP与用户之间的连接关系作为BP神经网络输出的预测向量,同时,针对BP神经网络初始化权值,提出了一种改进的自适应遗传算法以提高算法的收敛速度和收敛性能。仿真结果表明,改进后的BP神经网络预测结果更接近于实际值,并且比全连接和启发式的AP选择方案具有更高的系统和速率。

智能增强的免授权多址接入技术

免授权多址接入技术是未来海量物联(IoT)场景的关键使能技术。在免授权接入系统中,由于用户和基站间缺少授权信息,易产生用户难识别以及用户间强干扰等问题,一方面可将免授权多址技术与非正交多址接入技术结合来缓解随机接入造成的用户干扰问题,另一方面也可以进一步利用人工智能技术强大的数据特征提取能力,对收发机算法进行优化,以有效降低用户碰撞概率,实现海量物联场景下的大规模通信。分析了当前未来移动通信网络中多址接入技术的需求、发展历程及研究现状。指出未来需要针对全场景进行接入技术拓展和智能技术弹性演进研究,以助力智能内生多址技术发展。

卫星物联网中多域联合活跃用户辨识方法

在卫星物联网上行免授权接入场景下,用户直接将数据发送给卫星,不需要进行动态资源分配,这将导致接收端难以事先区分活跃用户。为恢复传输数据,需进行活跃用户检测(AUD)。目前,多使用码域方法进行活跃用户辨识,但物联网密度远超移动通信用户,仅依靠码域辨识会导致地址码维度激增,降低帧效率,并且较多采集类与监测类物联网终端自身能力弱,无法实现自身位置的上报,导致这一维接入辅助信息的缺失,不利于活跃用户检测的性能提升。本文面向未来星载相控阵发展趋势,引入空域辨识思想,通过空域与码域的级联辨识,采用多域联合方法进行活跃用户检测。仿真结果表明,本文方法能够提升地址码冲突时的辨识能力。

高校图书馆基于Open Access学术信息交流服务刍议

OA是一种全新理念的网络出版模式和学术信息交流模式。论文探讨了高校图书馆学术信息交流在OA环境中所面临的机遇和挑战,具体分析了OA的影响,以及高校图书馆应如何利用OA提升服务能力和质量。

无蜂窝大规模MIMO中的大规模随机接入

研究了以用户为中心的无蜂窝大规模多输入多输出(MIMO)架构下的大规模随机接入方案。为实现可扩展架构,讨论了接入点(AP)与用户设备(UE)的关联以及AP的分簇方法。针对活跃用户检测(AUD),一种基于最大似然检测(ML)的方案被提出以获取活跃用户。通过调整阈值,可以得到不同精度的检测结果。利用AUD的检测用户集合,系统利用基于狄利克雷过程的稀疏贝叶斯学习(DP-SBL)完成信道估计(CE)。该算法可以充分利用AP的空间聚散特性,提高系统准确性。基于以上工作,我们提出了联合AUD和CE算法。仿真结果验证了所提方案在性能上的优越性。

无障碍慕课的发展与挑战:基于国际研究的系统性文献综述

提高慕课的普惠性和包容性是慕课建设发展中的重要课题,也是确保残障人士平等享有学习权利的重要保障。文章基于国际研究视角采用系统性文献综述法,选取Web of Science、Scopus和ERIC数据库中2017—2022年的17篇相关实证研究论文进行统计分析。研究发现:无障碍慕课在平台设计、技术支持和对学习者特定类型的适应方面存在困难,主要是缺乏相关政策法规的支持、辅助技术工具的配套以及对残障用户需求的深入了解;国际上目前针对无障碍慕课评估的指南和标准主要依据Web内容无障碍指南(WCAG)、创作工具辅助功能指南(ATAG)、用户代理辅助功能指南(UAAG)以及ISO系列规范,需要加快推动评估指南、标准的修订和完善;无障碍慕课开发设计的核心要求是基于通用性和包容性原则,以残障用户为中心,提供多样化的资源和选择,以满足不同残障用户的需求和偏好。最后,文章探讨了推动我国无障碍慕课建设与发展的启示。

浅谈县城无障碍环境创建思路——以闽清县梅溪镇无障碍项目为例

在目前无障碍环境发展建设过程中,无障碍设施存在却不实用的问题屡见不鲜,文章通过现场走访调研,梳理现状场地问题,从顶层规划设计、建设细节以及管理维护三个方面重点提出无障碍线路的规划与统筹、无障碍设施规范化、精细化以及无障碍社会氛围营造三方面的创建措施,从而为闽清县无障碍环境创建工作提供参考。

医疗建筑无障碍设计要点分析

通过分析医疗建筑无障碍设计的要点,以提升医疗设施的可访问性和舒适性。在医疗建筑设计中,考虑到各种残障人士的需求是至关重要的。本文针对无障碍设计中常见的问题,如通道宽度、斜坡倾斜度和卫生设施高度等进行了深入讨论。此外,文中还探讨了利用先进技术,如智能导航系统和智能电梯,来提升医疗建筑的无障碍性。最后总结了一些实践经验和建议,以指导未来医疗建筑的设计和改进。

Neighbor-Aware Multiple Access Protocol for 5G m MTC Applications

In order to support massive Machine Type Communication(mMTC) applications in future Fifth Generation(5G) systems,a key technical challenge is to design a highly effective multiple access protocol for massive connection requests and huge traffic load from all kinds of smart devices,e.g.bike,watch,phone,ring,glasses,shoes,etc..To solve this hard problem in distributed scenarios with massive competing devices,this paper proposes and evaluates a Neighbor-Aware Multiple Access(NAMA) protocol,which is scalable and adaptive to different connectivity size and traffic load.By exploiting acknowledgement signals broadcasted from the neighboring devices with successful packet transmissions,NAMA is able to turn itself from a contention-based random access protocol to become a contention-free deterministic access protocol with particular transmission schedules for all neighboring devices after a short transition period.The performance of NAMA is fully evaluated from random state to deterministic state through extensive computer simulations under different network sizes and Contention Window(CW)settings.Compared with traditional IEEE802.11 Distributed Coordination Function(DCF),for a crowded network with 50 devices,NAMA can greatly improve system throughput and energy efficiency by more than 110%and210%,respectively,while reducing average access delay by 53%in the deterministic state.

On Uplink Non-Orthogonal Multiple Access for 5G：Opportunities and Challenges

In this paper,the concept of grantfree non-orthogonal multiple access(NOMA) for uplink data transmission is elaborated.NOMA in combination with grant-free can be applied to ultra reliability low latency communication(URLLC),massive machine type communication(m MTC),enhanced mobile broadband(e MBB) small packet and two-step random-access channel(RACH) scenarios.The advantages of grant-free NOMA are low latency and signaling overhead,high access capability and efficient resource utilization.Candidate uplink NOMA schemes are summarized and preliminary comparison among a subset of schemes are presented.Furthermore,design aspects for grant-free NOMA are discussed,with special notes on particular issues such as blind UE identification and transmitter/receiver(Tx/Rx) impairments in realistic deployment.

无蜂窝毫米波大规模MIMO系统基于深度强化学习的节能睡眠策略

为了提升无蜂窝毫米波大规模MIMO(Cell-Free millimeter-Wave massive MIMO,CF mmWave mMIMO)系统总能量效率,本文研究时变信道环境中接入点(Access Point,AP)睡眠节能机制.将AP开关切换(AP Switch ONOFF,ASO)策略看作一个马尔可夫决策过程,使用深度强化学习(Deep Reinforcement Learning,DRL)工具解决AP开关问题.引入干扰感知技术和局部敏感哈希检索方法减少代理与复杂环境的交互以及样本偏差,构造了一个新的效用函数,在严格用户服务质量(Quality of Service,QoS)约束下更好地权衡总能效和可达速率性能.通过对效用函数离散化分级处理,将状态空间映射为更小的分级状态空间,以加快决斗深度Q网络(Dueling Deep Q-Network,Dueling DQN)的收敛速度.仿真结果证明了该方案的稳定性、收敛性和严格QoS约束下的总能效性能优势.

High uniformity and forming-free ZnO-based transparent RRAM with HfO_x inserting layer

The impacts of HfOx inserting layer thickness on the electrical properties of the ZnO-based transparent resistance random access memory （TRRAM） device were investigated in this paper. The bipolar resistive switching behavior of a single ZnO film and bilayer HfOx/ZnO films as active layers for TRRAM devices was demonstrated. It was revealed that the bilayer TRRAM device with a 10-nm HfOx inserted layer had a more stable resistive switching behavior than other devices including the single layer device, as well as being forming free, and the transmittance was more than 80% in the visible region. For the HfOx/ZnO devices, the current conduction behavior was dominated by the space-charge-limited current mechanism in the low resistive state （LRS） and Schottky emission in the high resistive state （HRS）, while the mechanism for single layer devices was controlled by ohmic conduction in the LRS and Poole-Frenkel emission in the HRS.

室内自由小区VLC协作的用户接入和功率动态调整方法

针对室内自由小区VLC网络照明和吞吐量联合优化困难的问题,该文提出VLC协作用户接入和功率动态调整(VCUA-DPA)方法。在用户接入阶段,设计考虑网络的负载均衡、用户速率需求和协作小区数目限制的用户和VLC协作的用户接入算法;在功率分配阶段,设计联合优化照明均匀度和系统吞吐量的功率动态调整分配算法。仿真结果表明,所提VCUA-DPA在明显提升系统吞吐量的同时能优化室内照明均匀度。

无蜂窝大规模MIMO网络下基于联邦学习的用户接入策略及能耗优化

针对无蜂窝大规模多输入多输出(CF-mMIMO)网络中用户如何选择接入点的问题,提出了一种基于信道排序的较差用户优先接入策略。首先,用户进行信道感知后对其信道质量和稳定性进行评估和排序,用户按照信道状态信息的顺序依次选择合适的接入点;其次,考虑到用户的能耗与数据安全等问题,采用联邦学习框架以增强用户的数据隐私安全,并提出一种基于能耗优化的交替优化变量算法,对多维变量进行优化,使系统总能耗最小化。仿真结果表明,相较于传统的大规模MIMO中用户为中心的接入策略,所提接入策略可使用户平均上行可达速率提升20%,信道较差用户的上行速率可提升2倍;在能耗优化方面,优化后的总能耗可降低50%以上。

我国无障碍电影发展的现状、障碍及其破解

2018年我国《残疾人保障法》修订后,残疾人对信息与作品的获取与可及性等权益和福利的保障受到高度关注;作为无障碍格式的特殊作品,无障碍电影的发展问题近年也成为电影界的热议话题。尽管我国已经在无障碍电影发展方面积累了若干经验,并且《马拉喀什条约》近期已在我国生效,但在无障碍电影的发展过程中仍存在一些尚待解决的问题,包括最突出的版权障碍问题。为此,对我国无障碍电影发展中的主要问题作深入研究并提出促进该产业发展的有效对策与路径,是十分重要且必要的。