A Pragmatic Approach to Product Costing Based on Standard Time Estimation

The major drawbacks of traditional approaches to product costing include lack of manufacturing knowledge, reliance on the detailed design description, poor cost function approximation and inability to update estimation algorithms by using actual cost data. Adopting the Activity-Based Costing (ABC) concept and based on estimated processing time, this paper proposes a pragmatic approach to product costing. The approach involves two stages, namely the preparatory stage and the estimation stage. A case study conducted in a refrigerator company is reported.

The time and frequency standard system for FAST receivers

This paper reports on the time and frequency standard system for the Five-hundred meter Aperture Spherical radio Telescope(FAST),including the system design,stability measurements and pulsar timing observations.The stability and drift rate of the frequency standard are calculated using 1-year monitoring data.The UTC-NIM Disciplined Oscillator(NIMDO)system improves the system time accuracy and stability to the level of 5 ns.Pulsar timing observations were carried out for several months.The weighted RMS of timing residuals reaches the level of less than 3.0μs.

Noether symmetry and conserved quantity for dynamical system with non-standard Lagrangians on time scales

This paper focuses on studying the Noether symmetry and the conserved quantity with non-standard Lagrangians, namely exponential Lagrangians and power-law Lagrangians on time scales. Firstly, for each case, the Hamilton prin- ciple based on the action with non-standard Lagrangians on time scales is established, with which the corresponding Euler-Lagrange equation is given. Secondly, according to the invariance of the Hamilton action under the infinitesimal transformation, the Noether theorem for the dynamical system with non-standard Lagrangians on time scales is established. The proof of the theorem consists of two steps. First, it is proved under the infinitesimal transformations of a special one-parameter group without transforming time. Second, utilizing the technique of time-re-parameterization, the Noether theorem in a general form is obtained. The Noether-type conserved quantities with non-standard Lagrangians in both clas- sical and discrete cases are given. Finally, an example in Friedmann-Robertson-Walker spacetime and an example about second order Duffing equation are given to illustrate the application of the results.

Estimation of Standard Operation Time of Flight Legs Based on Clustering and Probability Analysis

A clustering algorithm and a probability statistics method were applied to different phases of a flight to analyze operation time during aircraft ground taxiing and airborne flight.And the clustering pattern,distribution characteristics and dynamically changing rules of the two phases were identified.Further,an estimate method was established to measure operation time of flight legs,with creative steps of calculating individual segment separately and then integrating them accordingly.The method can both objectively and dynamically measure operation time,and accurately reflect real situation.It helps to better utilize airport slot resources and provides a strong support for air traffic flow management when scheduling flight plan in strategic and pre-tactic phases.

Construction and evaluation of reference standards for detection and quantification of Klebsiella pneumoniae using real-time PCR

Objective To construct reference standards for detection and quantification of Klebsiella pneumoniae(K.pneumoniae)with SYBR Green I-based real-time PCR assay.Methods Primers were designed based on the published sequence of the phoE gene of K.pneumoniae.The standard was prepared by cell culture,PCR and T-A clone methods,and was identified by colony PCR and DNA sequencing.Results The standard curve showed a very good linear negative regression between threshold cycle(Ct)and Log starting quantity of copy number.The detection range was from 5.2 to 5.2×106 copies per reaction,and the detection limit was 6 copies per reaction.The coefficients of variance(CVs)of three parallel experiments were in the range of 0.05%-0.91%.Conclusion The reference standards have high stability and reproducibility.They can be used in the quantitative detection of K.pneumoniae.

Generation and Application of A Standardized Load-Time History to Tubular T-joints in Offshore Platforms

Marine structures are mostly made of metals and always experience complex random loading during their service periods. The fatigue crack growth behaviors of metal materials have been proved from laboratory tests to be sensitive to the loading sequence encountered. In order to take account of the loading sequence effect, fatigue life prediction should be based on fatigue crack propagation（FCP） theory rather than the currently used cumulative fatigue damage（CFD） theory. A unified fatigue life prediction（UFLP） method for marine structures has been proposed by the authors＇ group. In order to apply the UFLP method for newly designed structures, authorities such as the classification societies should provide a standardized load-time history（SLH） such as the TWIST and FALSTAFF sequences for transport and fighter aircraft. This paper mainly aims at proposing a procedure to generate the SLHs for marine structures based on a short-term loading sample and to provide an illustration on how to use the presented SLH to a typical tubular T-joint in an offshore platform based on the UFLP method.

An improved formula for standard hypoxia tolerance time to evaluate hypoxic tolerance in mice

Background: Hypoxia is a primary cause of mountain sickness and a common pathological condition in patients with heart failure, shock, stroke, and chronic obstructive pulmonary disease(COPD). Thus far, little advancement in countering hypoxic damage has been achieved, and one of the main reasons is the absence of an ideal algorithm or calculation method to normalize hypoxia tolerance scores when evaluating an animal model. In this study, we improved a traditional calculation formula for assessment of hypoxia tolerance.Methods: We used a sealed bottle model in which the oxygen is gradually consumed by a mouse inside. To evaluate the hypoxia tolerance of mice, the survival time(ST) of the mouse is recorded and was used to calculate standard hypoxia tolerance time(STT) and adjusted standard hypoxia tolerance time(ASTT). Mice administered with methazolamide and saline were used as positive and negative controls, respectively.Results: Since mice were grouped according to either body weight(BW) or bottle volume, we found a strongly negative correlation between STT and BW instead of between STT and bottle volume, suggesting that different BWs could cause false positive or negative errors in the STT results. Furthermore, both false positive and negative errors could be rectified when ASTT was used as the evaluation index. Screening for anti-hypoxic medicines by using mice as the experimental subjects would provide more credible results with the improved ASTT method than with the STT method.Conclusions: ASTT could be a better index than STT for the evaluation of hypoxia tolerance abilities as it could eliminate the impact of animal BW.

Investigating the Use of <i>Jatropha</i>Biodiesel in Compression Ignition Engines by Comparing Effects of Storage Time on Its Properties with the Standard Properties of Fossil-Diesel and Properties of Quality Biodiesel

Effects of storage time on some properties of jatropha biodiesel were investigated over the storage time of 0 to 8 weeks at the temperature of 25℃. Such properties as water content and density were found to increase at the rates of 5 ppm and 14 kg/m3 per week respectively. These rates translate into property values which compare closely with the standard properties of fossil-diesel and properties of quality biodiesel. As a result, the jatropha biodiesel can be used as alternative fuel to fossil-diesel in compression ignition engines within 8 weeks of its production. However, the calorific value and flash point of the biodiesel decreased at the rate of 1.4℃ and 2.5 MJ/kg per week respectively. Although the flash point was within the acceptable level for quality biodiesel, the calorific values were abnormally higher than the values for quality biodiesel of about 38.7 MJ/kg. With the exception of the calorific values, the other properties were not reasonably affected.

China National Standards on Nano-Materials Issued for the First Time

On February 28th, 2005, AQSIQ (the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China), and SAC (the Standardization Administration of P. R. China)jointly hosted the press conference on seven items of national standards on nano-materials in Beijing. The seven items of national standards were approved on Sept. 29th and Dec. 27th, 2004 respectively by SAC, and publicized in Jan. 2005. They will be formally put into practice from April 1st, 2005.

时空异质性视角下华北地区碳足迹评估及驱动因子分析

碳足迹是衡量碳排放的重要指标,削减碳足迹是实现“双碳”目标的前提条件。华北地区作为我国高耗能、高排放的集中区域,客观量化碳足迹并探究主要驱动因子对加快推进碳减排具有重要意义。为此,论文基于IPCC法对华北地区“十五”至“十三五”期间的碳足迹进行测算,运用标准差椭圆分析碳足迹的分布及转移特征,使用地理探测器识别碳足迹的主要驱动因子。研究发现:(1)“十五”至“十三五”期间碳足迹总量经历了“先增长—后下降”两个阶段,由“十五”期间的425452万吨上升至1066353万吨,而后逐渐下降到“十三五”期间的898908万吨。(2)标准差椭圆呈稳定的“南—北”分布,重心分布于山西大同和河北张家口之间,呈向西北方向偏移趋势,已偏移72.56千米。(3)能源强度、产业结构、城镇化率对碳足迹驱动因子解释力度较大,且关键交互因子均含有能源强度、产业结构、研发投入。华北地区不同时期碳足迹分布及影响因子存在时空差异,在制定碳减排政策时应充分考虑区域碳足迹的时空异质性。

基于OSEKTime的共存模型的改进与实现

OSEKTime规范提出了基于时间触发操作系统与基于OSEK/VDX标准实现的操作系统的共存模型。在分析OSEKTime规范的基础上,针对该规范的消息触发任务存在着非实时性问题,提出并实现了一种合理的、能与OS-EK OS共存的实时时间触发操作系统,确保了时间触发任务的实时性和对消息触发任务的死限时间内的及时处理。

Real-time PCR检测风疹病毒方法学建立及临床应用

为了建立一种能广泛应用于临床快速、简便、灵敏度和特异性较好的风疹病毒（RV）定量诊断方法。针对RV基因保守序列设计两对引物和一条荧光双标记探针。将PCR扩增所得到的产物片段克隆，作为定量检测的标准品，进行Real—timePCR检测，绘制标准曲线。将此方法和ELISA试剂盒平行检测50份孕妇血清，评估两种方法检出阳性率的差异显著性。Real—timePCR法能较好地检出RVcDNA载量。曲线的相关系数（r）为0．998，可检测线性范围大约在10^3～10^9copies／μl，灵敏度接近10^3copies／μl；批间、批内CV值分别为3．36％、0．94％；也有较好的特异性。与经典的ELISA方法相比，有显著性差异。Real—timePCR方法操作简单、快速，并能避免PCR后处理导致的假阳性污染，实现实时定量。此方法对RV感染的临床诊断和疗效判断等方面有较大的指导意义。

A Computer Vision-Based Model for Automatic Motion Time Study

Motion time study is employed by manufacturing industries to determine operation time.An accurate estimate of operation time is crucial for effective process improvement and production planning.Traditional motion time study is conducted by human analysts with stopwatches,which may be exposed to human errors.In this paper,an automated time study model based on computer vision is proposed.The model integrates a convolutional neural network,which analyzes a video of a manual operation to classify work elements in each video frame,with a time study model that automatically estimates the work element times.An experiment is conducted using a grayscale video and a color video of a manual assembly operation.The work element times from the model are statistically compared to the reference work element time values.The result shows no statistical difference among the time data,which clearly demonstrates the effectiveness of the proposed model.

金黄色葡萄球菌基因表达的DNA扣除法Real-time RT PCR相对定量分析

【目的】金黄色葡萄球菌作为一种分布广泛的致病微生物和研究革兰氏阳性菌遗传背景的模式菌株,利用real-time RT PCR对相关毒素及调控基因进行表达定量分析,在生物、医学、食品检测等领域具有较大研究价值。【方法】对制备好的反转录(RT,含有cDNA和DNA)和非反转录(RT—,仅含DNA)样品进行Real-time PCR检测,根据经典(1+E)—△△Ct相对定量算法并结合PCR效率公式建立一种基因表达相对定量分析的DNA扣除法,将得到的Ct值转换为各样品含量,从RT样品中扣除RT—样品的量,无需DNaseⅠ酶解处理就可以去除DNA的影响,RT—样品的检测结果还可同时作为稳定的DNA内参。【结果】采用以上方法分析金黄色葡萄球菌肠毒素A基因(sea)、16S rRNA和RNAⅢ的表达情况,在含有葡萄糖的NB培养基中sea的相对转录水平随着葡萄糖浓度的增大而升高,RNAⅢ的相对转录水平随葡萄糖浓度的变化而产生小幅度的波动,16S rRNA在菌体生长初期时的表达量较为稳定;与绝对定量法比较,结果差异较小(均小于15%),且差异不显著(p>0.05)。【结论】这种基于DNA扣除法的Real-time RT PCR相对定量方法可以有效的对金黄色葡萄球菌的基因表达进行分析。

不同比对方式下的洲际标准时间复现性能分析

中国科学院国家授时中心研制的标准时间复现系统具备支持洲际用户对标准时间频率信号的需求。本文以位于欧洲白俄罗斯明斯克的复现终端为分析对象,分析了共视、全视不同比对方式对复现时频信号性能的影响。对于洲际范围的时间复现,复现终端与参考端共同可视卫星数变少。单一卫星导航系统可利用的共视卫星数明显减少,GPS/BDS共视可明显增加可视卫星数量,提高共视时间比对精度,全视比对对两地共同可视卫星数没有要求。分析结果表明,单GPS全视比对就可以达到优于GPS/BDS的共视比对复现效果。受BDS卫星星间偏差的影响,基于单BDS全视比对的复现效果比GPS稍差,GPS/BDS全视比对效果略有改善。复现终端运行在GPS/BDS共视比对融合GPS全视比对模式复现的时频信号的性能最优,可以满足洲际范围内5 ns的时间同步要求,为后续洲际大尺度范围的标准时间复现终端的运行模式提供参考。

美国加州车网互动政策、标准与市场机制最新进展及其启示

电动汽车与电网互动(简称“车网互动”)可以释放电动汽车作为灵活性资源的潜力,能够有效提升电网调峰能力、促进高比例可再生能源消纳、提升电动汽车用户经济收益,日益受到各方重视。美国加利福尼亚州(简称“加州”)近些年在推动电动汽车与电网互动发展方面做了大量工作,取得了重要进展。首先,文中介绍了加州在电动汽车与电网互动配套政策法规方面的最新动向;之后,从技术标准、市场机制两方面介绍了加州在电动汽车与电网互动相关基础工作方面的最新进展;最后,结合中国电动汽车与电网互动发展实际提出了有关建议。

多维邻近性对国际技术标准生存时间的影响研究——基于ITU国际技术标准生存分析

在技术快速变革和迭代的时代背景下,构建技术标准联盟是各类组织适应技术快速发展的必要手段。技术标准联盟的组织构成正在朝着跨国化和多样化发展,联盟成员间特征差异程度的提升对技术标准生存时间产生了重要影响。根据协同创新理论,基于2010—2021年ITU国际技术标准联盟的相关数据,运用生存分析方法,分析多维邻近性与技术标准生存时间的内在关联。结果表明,地理邻近性与技术邻近性能显著提高ITU国际技术标准生存时间;组织邻近性与制度邻近性对ITU国际技术标准生存时间具有显著负向影响;地理邻近性与技术邻近性、组织邻近性与制度邻近性的交互作用对ITU国际技术标准生存时间具有显著负向影响,地理邻近性与组织邻近性、地理邻近性与制度邻近性、技术邻近性与组织邻近性以及技术邻近性与制度邻近性的交互作用对ITU国际技术标准生存时间具有显著正向影响。研究有助于深化对技术标准联盟协同创新的理论解释,丰富了技术标准生存时间驱动因素的理论成果,可为我国信息和通信技术行业国际技术标准制定的管理实践提供重要参考。

NIM5驾驭氢钟守时能力分析

时间频率量值源头的独立自主是建设我国综合PNT体系的重要基础。为进一步评估基于我国国家秒长基准的原子时标守时能力,利用改进的有限脉冲响应钟差预测与频率调控方法,对激光冷却铯原子喷泉钟与氢钟的频差实测数据进行后处理,分别产生了自主型时标和溯源型时标。通过国际原子时合作链路将两个时标与协调世界时进行了长期比对实验,结果表明:2021年12月~2022年12月期间,两个时标的时间偏差均优于±4 ns、频率稳定度均优于8×10^(-16)/5 d。

Including Space-Time in the Extended Group Cl3* of Relativistic Form-Invariance

The inclusion of space-time in the extended group of relativistic form-invariance, Cl3*, is specified as the inclusion of the whole space-time manifold in this multiplicative Lie group. First physical results presented here are: the geometric origin of the time arrow, a better understanding of the non-simultaneity in optics and a mainly geometric origin for the universe expansion, and its recent acceleration.

低温弱光胁迫下茄子幼苗实时荧光定量PCR内参基因的筛选与评价

为了探索茄子Solanum melongena L.的基因表达模式,利用qRT-PCR方法分析了茄子ACT、EF1α、TUA、TUB、GAPDH、eIF、UBQ、UBI3、PP2A、CYP、RPL28、L25、SAND、TBP、DNAJ、APRT、EXP、CAC、HSP20和CysPro 20个候选内参基因mRNA的表达差异情况,并运用GeNorm、NormFinder和BestKeeper 3种计算方法评价茄子20个候选内参基因在低温、弱光、低温弱光叶片样品中的表达稳定性。结果表明:茄子20个候选内参基因荧光定量引物扩增效率(E)数值在96.8%~117.6%,相关系数(R^(2))介于0.9688~0.9999,扩增效率良好,扩增反应具有高度的专一性,引物能特异性扩增,特异性好,均为单峰,样品间扩增曲线重复性强,可用于qRT-PCR扩增。茄子20个候选内参基因C_(T)值表达丰度分析,发现茄子20个候选内参基因平均CT值在19.76~31.20。3种计算方法的综合评价分析结果显示,TBP基因在所有样本中为最稳定的内参基因。研究可为茄子低温、弱光和低温弱光胁迫下基因特异性表达研究提供了合适的内参基因。