考虑双程声径的走航式水下差分定位方法

水下声学定位中存在收发时刻位置差、声速误差等系统性误差,传统方法无法同时削弱这些误差的影响。针对该问题,本文采用历元间差分削弱系统误差的影响,给出了一种考虑双程声径的走航式水下差分定位方法,对其函数、随机模型进行了推导,并通过仿真和实测算例验证本方法的定位精度水平。结果表明:传统单程非差、单程差分、双程非差以及考虑双程声径的差分方法,对应的观测值残差均方根误差分别为3.460、3.396、1.692和1.471 m,证明本方法有效提高了水下定位的精度,且较适用于深海区域的水下定位。

Analysis of Starbucks in China

Since coffee is gradually becoming popular in China,the promising market prospect that China’s coffee market has is appealing to multiple companies.Starbucks,a successful business magnate in the coffee market around the globe,occupies a huge market share in China’s coffee market.Nevertheless,numerous competitors,especially domestic coffee brands in China,and the hit caused by the COVID-19 epidemic put great pressure on the company.Furthermore,the company itself also has some weaknesses currently,which can affect the corporation negatively.As a result,based on the background of China’s coffee market and the enterprise’s own situation,this article mainly pays attention to three vulnerabilities,giving an analysis of these problems,and some suggestions will be provided correspondingly.

猪圆环病毒Ⅱ型Cap蛋白的原核表达、纯化和鉴定

目的对猪圆环病毒(Porcine circovirus,PCV)Cap蛋白的主要B细胞抗原表位进行分析,构建Cap表达多表位的原核表达系统,并对表达的目的蛋白进行分析,为猪圆环病毒诊断试剂开发奠定基础。方法设计并合成PCV2Cap基因,与PET-28a(+)载体连接后并转入大肠杆菌BL21(DE3)中构建重组质粒PET-28(a)-Cap,对重组质粒进行诱导表达获得重组蛋白,通过His亲和层析柱对重组蛋白进行纯化。结果重组质粒在大肠杆菌中成功表达,蛋白质分子量约为17.4 k Da,与预期相符;Western blot结果显示,重组蛋白可以与猪圆环病毒阳性血清发生特异性结合。结论PCV2 Cap蛋白的表达纯化为圆环病毒血清抗体诊断方法的建立,进而为养殖场有效监控猪圆环病毒的免疫保护情况奠定基础。