Pichia pastoris表达系统提高表达量的几个关键点

Pichia pastoris是近年来迅速发展的一种真核生物表达宿主,有着广阔的应用前景．本文从提高Ppastoris表达重组蛋白产量的角度,就启动子、高拷贝重组子、密码子偏爱、宿主菌和高密度发酵等方面的优化进行了综述．     

一种基于距离比值的支持向量机增量训练算法

由于支持向量机具有较好地学习性能和泛化能力,目前已经得到了广泛的应用。如何使支持向量机进行有效的增量学习是目前支持向量机应用中需要解决的问题。深入研究了支持向量分布特点,提出了一种新的支持向量机增量训练淘汰机制——距离比值算法。该算法根据遗忘规则,设定一个合适的参数,按距离比值法中的定义计算各个样本中心距离与其到最优分类面距离的比值,舍弃对后续训练影响不大的样本,即可对训练数据进行有效的淘汰。对标准数据集的实验结果表明,使用该方法进行增量训练在保证分类精度的同时,能有效地提高训练速度。     

一种改进的关联规则增量更新算法

数据挖掘技术引起了数据库和人工智能等领域的专家和学者的广泛关注。关联规则的挖掘是数据挖掘研究的一个重要领域,本文分析了经典的增量更新算法FUP的不足,提出了一种改进的增量更新算法EFUP,详细论述算法思想,并与FUP算法比较分析,表明了该算法的优越性。     

浅析统一软件开发过程

本文对统一软件开发过程的发展历程,统一软件开发过程的用例驱动、以架构为中心、迭代和增量进行阐述,对统一软件开发过程的优缺点进行了讨论.     

UIO序列的启发式算法

UIO序列是对有限状态机进行功能测试的有效手段 ,在 VLSI设计、通信协议等时序系统中有很强的实际应用背景。文章基于可区分状态组这一概念设计了一个搜索算法 ,进一步利用搜索信息建立了一个基于“小于”关系的启发策略 ,有效的剪枝策略的设计将尽可能消除没有意义的搜索分枝 ,新设计出的多路 OPEN/CLOSED表存储机制也加快了相关的判别和处理过程。这些措施改进了搜索过程 ,减少了搜索信息的产生 ,提高了搜索速度。该算法与以往的算法相比 ,在时间和空间两方面都得到了很大改进。     

场分析法与阻抗叠加方法在速调管输出腔间隙阻抗计算中的应用

 从分析速调管输出回路的电磁场分量入手,结合微波电路理论,提出了计算速调管输出回路间隙阻抗的场分析法。对于在谐振模式交叠频带上,群聚电子束电流同时与各模式的阻抗相作用,总阻抗是各模式阻抗的代数叠加的情况,提出了阻抗叠加方法。该方法原则上可求解任意给定间隙电阻所对应的间隙电抗值。计算表明,场分析法与等效间隙阻抗法计算结果最大相对误差为1.5％,阻抗叠加方法计算结果与冷测数据最大相对误差为10％。分析表明,多个谐振模式的引进是速调管输出腔加载滤波器展宽频带的物理实质。     

以氮气为载气COIL的设计与实验

 根据以氮气为载气的特殊要求，对kW级氧碘化学激光器（COIL）装置的结构进行了有针对性的设计和实验研究。在氯气流量为140mol/s的情况下, 获得了2.6kW的功率, 相应的化学效率为20.4%, 喷管出口能流密度达到了74W/cm²。这一结果达到了以氦气为载气COIL的水平。     

Passive Attitude Control of Flexible Spacecraft from Quaternion Measurements

In this work, we propose a dynamic controller for a spacecraft with flexible appendages and based on attitude measurements. This control ensures the asymptotic fulfillment of the objectives in the case of rest-to-rest maneuvers when a failure occurs on the accelerometer sensors, so that the angular velocity is not available for feedback. Also, it is assumed that the modal variables describing the flexible elements are not measured. This is a lower level controller and is to be selected at the higher level by a supervisor when an emergency situation is detected.     

Multi-objectives for incremental cell formation problem

Over the past three decades considerable amount of research work has been reported in the literature of Group Technology (GT). Most of the research work is concerned with formation of machine cells and part families. This is because cell formation is considered to be the most complex and the most important aspect of Cellular Manufacturing System (CMS). Due to NP completeness of cell formation problem, many heuristics have been developed. These heuristics are developed for both single as well as multiple objectives for the comprehensive cell formation. Here all part types and machine types are considered at a time for cell conversion and that all cells are designed at a single point in time. But planning and implementation of most cell conversions in industry are incremental ones, and not comprehensive. This issue has not been addressed in GT literature adequately. In this paper we consider multiple objectives for incremental cell formation and develop, a lexicographic based simulated annealing algorithm. The performance of the algorithm is tested over several data sets by taking different initial feasible solutions generated using different heuristics.     

LOW POWER MEASUREMENTS ON THE NEW RF OUTPUT SYSTEM OF A 170 GHZ, 2 MW COAXIAL CAVITY GYROTRON

The design of the quasi optical (q. o.) RF output system for the first industrial prototype of the European 170 GHz, 2 MW, CW coaxial cavity gyrotron for electron cyclotron heating and current drive in ITER has been verified at a low power level. Results of measurements with a high quality TE_34,19-mode generator are in good agreement with the design calculations. This strengthens the confidence both to the employed design codes and to the manufacturing quality of the launcher and mirrors.