Influence of Sows Farrowing Performance on Growth of 21-Day-Old Weaned Piglets and Their Correlation Research

[ Objective ] To study the influence of sows farrowing performance on the growth of 21-day-old weaned piglets and their correlation. [ Methods ] A total of 1 350 Duroc x Landrace Yorkshire piglets produced by 2-6 fetal Landrace x Yorkshire sows from 118 litters within a month were selected to be the test objects. All the newborn piglets were lactated by their parent sows. The test groups were divided according to different numbers （6 - 17） of live birth. The variance analysis were conducted on birth weight, litter weight at birth, number of 21-day-old weaning piglets, weaning weight, weaninl2g weight of litter, weaning survival rate and relative individual weight gain among different weeks. [ Results] Sows farrowing performance had significant influence on the growth performance of 21- day-old piglets. However, the influences among different traits varied, some were even on the contrary. With the increase of the number of live birth, the birth weight, weaning weight of litter and weaning survival rate showed a decline trend. And when the number of live birth was equal or more than 14, the weaning sur- vival rate dropped to below 90% （P 〈 0.01 ） ; when the number of live birth was 13, the litter weight at birth and weaning weight of litter reached the peak. What- ever the number of live birth increased or decreased, the weaning weight showed a regular decline trend. [ Conclusions] When the number of live birth changed from 11 to 13, the maximum values of the economic indicator （weaning weight of litter） and the technical specifications （weaning survival rate） were achieved.

宽带数字波束形成中的分数延时滤波器设计优化

在宽带数字波束形成处理中,一个关键问题是对阵列天线接收到的信号进行包络延时补偿。解决该问题的基本方法是通过分数延时滤波器对输入信号进行延时。本文主要讨论Farrow结构的分数延时滤波器设计优化方法,以便于工程应用。

基于立方Farrow结构的插值细搜频偏估计算法

在高动态通信环境中,由相对运动引起的多普勒频移会在接收机下变频所得的基带信号中引入残留频偏,致使基带信号的相位发生偏离。对频偏进行精确估计是提升高动态环境通信质量的重要途径。传统方法通常通过对快速傅里叶变换(Fast Fourier Transform,FFT)后所得频谱进行一维搜索来估计载波频偏值,只能估计整数倍频点。为了进一步提高频偏估计的精度,本文提出了一种基于立方Farrow结构的插值细搜(Interpolation Detail Search, IDS)算法。仿真结果表明,此算法仅在16倍插值条件下就得到了逼近克拉美罗界(Cramer-Rao Bounds,CRB)的频偏估计性能,信噪比精度损失仅为1.2 dB,具有良好的估计性能。

基于稀疏约束的低复杂度可变分数时延滤波器

针对基于Farrow结构的可变分数时延(Variable fractional delay,VFD)滤波器需求解大量子滤波器系数这一关键问题,本文将稀疏约束理论引入滤波器的权系数优化中,研究具有稀疏系数的Farrow结构滤波器。在极大极小(Minimax)准则下,通过添加L1正则化约束项改进权系数优化模型,在系数(反)对称性基础上进一步增加系数的稀疏度。然后,采用交替方向乘子法(Alternating direction method of multipliers,ADMM)进行权系数迭代求解。仿真实验表明,本文提出的基于稀疏约束的VFD滤波器在保证高延迟精度的同时,乘法器和加法器分别减少了47.69%和58.60%,极大地降低了系统运算量以及复杂度。

Isomaltooligosaccharide and Bacillus regulate the duration of farrowing and weaning-estrous interval in sows during the perinatal period by changing the gut microbiota of sows

This study investigated the effects of isomaltooligosaccharide(IMO)and Bacillus in perinatal diets on the duration of farrowing and post-weaning estrus,serum reproductive hormone concentrations,and gut microbiota and its metabolites of sows.Multiparous sows(n=130)were fed diets without IMO(control,CON group),or diets containing only IMO(IMO group),IMO and Bacillus subtilis(IMOS group),IMO and Bacillus licheniformis(IMOL group),and IMO and B.subtilis and B.licheniformis(IMOSL group),respectively.The results indicate that the duration of farrowing and post-weaning estrus was shorter in sows in the IMOS,IMOL,and IMOSL groups,and the weaning-estrous interval was lower in sows in the IMOL greoup.In addition,the lowest fecal score was observed in the IMOL group during d 106 to 112 of gestation.Sows in most of the treatment groups had a higher concentration of serum prolactin and prostaglandin at farrowing,but a lower serum concentration of estradiol,oxytocin,and progesterone on d 18 of lactation than sows in the CON group.The treatment groups had a higher abundance of Candidatus Methanoplasma and Bacillus and a lower abundance of Escherichia-Shigella in their feces at farrowing.Furthermore,the treatment groups had higher concentrations of total short-chain fatty acids(SCFA)in feces at farrowing and a higher concentration of branched fatty acids in feces on d 18 of lactation.Furthermore,the abun-dance of Bacillus in feces was positively correlated with serum prostaglandin concentrations and fecal total SCFA of sows at farrowing,but was negatively correlated with the duration of farrowing.Overall,dietary IMO and Bacillus supplementation affected the concentration of serum reproductive hormones and the duration of farrowing and post-weaning estrus,and the gut microbiota is a key factor.

Effects of water-cooled cover on physiological and production parameters of farrowing sows under hot and humid climates

The hot and humid climates,as encountered in the southern region of China with the open housing,can adversely impact the sows undergoing heat stress during the most vulnerable period at lactation.Hence,a water-cooled cover system(WCCs)for local cooling has essential practical value to improve productivity.The WCCs was developed for the sow crate of lactating sows separately,which performance was validated with the cooling efficiency in the sow occupied zone(SOZ)and physiological parameters.The results showed that the WCCs for the farrowing sows using aluminium plastic tubes connected in series could reach an appropriate cooling performance in adjacent units.The WCCs could decrease the SOZ air temperature by 3.0-4.5℃under the extremely hot climate when the indoor air temperature was 37℃,and maintain a suitable range(25-30℃)under the typical hot climate(<35℃).The respiration rate and skin temperature of farrowing sows had no significant difference between treatment group(WCC)and control group(sprinkle cooling)when the air temperature was below 30℃,but had a significant difference(p<0.05)when air temperature rose above 30℃.The control sows drank more during hot weather,and the feed intake was significantly lower than the sows with the WCCs(p<0.01).It was concluded that the WCCs could alleviate the heat stress of farrowing sows during typical hot climate.

基于Farrow结构的分数延时滤波器FPGA设计与实现

随着数字信号处理技术的不断发展,可变分数延时滤波器在采样率转换、时延估计、图像插值、雷达波束形成等高速信号处理系统中得到广泛应用,在FPGA中设计实现高效可靠的分数延时滤波器具有重要意义。本文介绍了Farrow结构的分数延时滤波器原理,基于Farrow滤波器由多个子滤波器构成的特殊结构,在FPGA中进行了设计与实现,并通过Matlab+Modelsim工具对设计的Farrow滤波器进行仿真分析,仿真结果与理论计算结果基本一致,相对误差在10-5量级,可以满足大部分工程应用需求。

一种双ADC垂直同步采样结构及其误差校正

航空航天、机械、声学、装备制造等领域对检测仪表的观测动态指标要求极高,甚至超出现有商用高分辨力数模转换器件的极限,因此,本文拟建立一种双ADC垂直同步采样的机制,通过数据流拼合的方式达到总动态范围扩展的目的。在双ADC硬件平台中,针对不同采样支路差异化所导致的量化数据延时误差,提出了一种基于拉格朗日插值Farrow结构滤波器的误差校正方法。仿真及硬件实验表明,本文提出的双ADC垂直同步采样架构将实验对象的动态范围提高了13.318 dB,同时本文提出的误差校正方法可以有效降低垂直同步采样通道之间的延时误差,进而使双ADC的动态范围扩展具备实用价值。

基于加权最小二乘法的分数延时滤波器设计

相较于传统的可变分数延时滤波器无法满足延时的实时变化,Farrow结构延时滤波器因其独特的结构可以灵活地调整时延且不需重新设计滤波器系数。以加权最小二乘法作为分数延时滤波器系数配置的基本方法,通过建立离散加权平方误差函数对滤波器系数的配置进行理论推导。并设计一种最小化幅度响应最大绝对误差的迭代判断条件来确定权重函数,用以更新滤波器系数来实现滤波器性能的优化。

基于FPGA的短波信号数字信道化设计与实现

短波通信凭借传输距离远、成本低等优势,在现代通信中占有极其重要的地位。在目前的无线电通信中,短波通信仍是最可靠和最有效的,在某些特殊领域具有不可替代性。因为带宽窄、信道多,短波信号常规数字信道化处理需要占用较多的现场可编程逻辑阵列(Filed Programmable Gate Array,FPGA)资源,造成硬件成本的浪费。针对短波信号数字信道化FPGA资源消耗严重问题,提出了一种基于FPGA实现的TPFT和Farrow结构的窄带信道化方法,介绍了窄带数字信道化的算法原理,阐述了窄带数字信道化的硬件实现结构,对板级最小测试系统进行了测试分析。在单片XC7VX690T FPGA中占用较少资源完成了短波信号多路信道化的工程实现,为多路窄带数字信道化提供了一种新的硬件实现思路。同时对其他信号的窄带数字信道化方法具有参考意义。

基于ADMM的Farrow结构宽带波束形成器鲁棒设计

针对经典滤波求和结构波束形成方法在目标声源位置变化且存在失配误差的实际场景中不适用的问题提出了Farrow结构波束形成器模型,并通过对白噪声增益进行约束实现了鲁棒设计。为进一步改进Farrow结构宽带波束形成器鲁棒设计规模大、耗时高的不足,提出采用交替方向乘子法进行迭代优化求解。仿真结果表明,所提设计方法能够实现指向实时可调并具备一定的抗干扰能力,相较于使用传统的CVX工具箱求解,该方法可以在保证良好空域滤波效果的同时有效提高运算效率。

一种时间交替ADC时间失配误差自适应校正方法

时间失配误差是时间交替并行采集系统的失配误差中最主要且影响最大的误差。针对该问题,提出了一种基于Farrow结构分数延迟滤波器结合自适应估计对时间失配误差进行数字校正的方法。分数延迟滤波器可以在有限带宽信号采样点之间进行插值。该方法可以对奈奎斯特频率以内的输入信号进行补偿校正,同时适用于任意通道数的时间交替ADC。仿真结果表明,该方法能够对时间失配误差进行精确估计,同时能够有效地抑制杂散分量,校正效果良好。最后,在实际的时间交替采集系统中验证了该方法的有效性。

一种基于Farrow滤波器的并行采样时间误差校正

用Farrow结构滤波器对并行采样信号进行时间误差校正,通过DSPBuilder软件将设计的滤波器模型转化为硬件语言,利于FPGA实现。此方法在时间误差改变的情况下也无需改变滤波器系数,易于实时校正,适用范围宽广。随着过采样倍数的增大或滤波器阶数的增加,校正后信号无杂散动态范围SFDR提升幅度增大。实验结果表明该方法能有效抑制时间误差所引入的杂散频谱,提高信号的无杂散动态范围,具有较高可行性。

采样率转换中Farrow滤波器实现结构研究

详细介绍了采样率转换的一种新的硬件实现结构:Farrow滤波器结构,同时也介绍了其派生的改进Farrow结构、TFS和改进TFS,并相互进行特性对比,仿真实验,结果表明Farrow结构是一种可实现任意分数延迟的高效、灵活的采样率转换结构,Farrow结构适于采样率提高,而TFS适于降采样率;对称改进结构降低复杂性。

用于中红外痕量气体检测的光电信号高速采集系统设计

在中红外波段,大多数气体分子吸收光谱的线宽都很窄,因此红外光电探测器输出信号为窄脉冲信号。对此脉冲信号的处理要求前置放大器必须兼具精度与速度,而对放大器输出信号的采集也需要在保证带宽的情况下尽量提高数字化的精度。本文中设计了高速并行采样电路,利用两片双通道高速ADC实现了1GSPS的采样速度与12bit的垂直分辨率。信号链的最后一环是FPGA数据处理电路,我们应用CORDIC算法对采集系统的时间误差进行了校正。本文最后给出了光电信号高速采集电路的设计与测试结果,在输入参考信号频率为100MHz时,采集系统整体信噪比达到60d B,无杂散动态范围达到70d B。

基于Farrow结构的恒定束宽时域波束形成器研究与实现

提出了一种基于Farrow结构的恒定束宽时域波束形成器,主要包括实现整数倍采样间隔延迟的数字延时单元、基于Farrow结构的高精度分数延时单元以及保证恒定束宽的幅度加权单元;理论分析了该波束形成器的原理,特点和优势;利用计算机仿真验证了该波束形成器的有效性和优越性;在C6748 DSP平台上的移植实现展示了该恒定束宽波束形成器的实现效率及实用性。

一种定标器的低硬件复杂度设计

将Farrow结构引入定标器插值算法模块,使四点分段抛物线插值器面积降到直接卷积实现方法的30%以下;结合Farrow结构的特点,提出了一种简单的插值位置系数产生方法;同时,还提出一种新型的存储器存取方式,可使缩放器垂直方向行存储单元总面积降低12.5%左右。该定标器已经在FPGA上通过验证,并作为IP嵌入到视频格式转换芯片中。

全数字接收机中一种基于并行流水线与快速FIR算法的插值滤波器结构及其实现

该文在对已有的拉格朗日立方插值滤波器Farrow结构进行分析和研究的基础上,使用了流水线技术和并行处理技术来提高滤波器的速度。在此基础上提出了基于快速FIR算法的结构,降低了并行的Farrow结构的复杂度。对该算法结构进行了仿真,并在FPGA上实现。分析结果表明,改进后的结构有更快的运行速度和更低的功耗。

VFD滤波器的导航信道模拟器动态时延模拟方法

针对卫星导航信道模拟器信号仿真中,传统伪距多普勒模拟方法瞬时控制精度差、滤波器资源占用较大的不足,提出了基于拉格朗日插值延迟滤波器及Farrow结构实现的伪距多普勒模拟方法。在分析信道模拟器系统架构的基础上,建立了多普勒模拟方法的模型,包括延时计算模块和可变延迟滤波器两部分。与多速率采样数字延迟滤波器方法比较,该方法滤波器系数个数约为后者的0.2%,并且改变时延特性时,仅需更新1个参数。信道模拟器实测数据结果表明使用该方法伪码多普勒模拟精度可以达到0.1mHz。

一种灵活高效的分数延迟数字滤波器

一般拉格朗日内插采用直接的FIR滤波器实现,虽然简单,但系数随延迟变化而变化,实现不灵活。对此提出一种更为灵活高效的实现结构:Farrow滤波器结构。Farrow滤波器结构及其对称的改进Farrow滤波器结构,不仅可应对变化的分数延迟,而且大大减少运算,提高运行效率。采用TMS320C64X芯片对拉格朗日内插的4种实现方式进行定点设计,实验结果表明:利用Farrow或改进Farrow滤波器结构实现分数延迟滤波器,不仅节约存储空间,而且容易使用软件流水,比FIR直接实现更能提高运算效率。