工商业用户计量管理系统在城市燃气的应用

在城市燃气管网输配中,与终端用户的贸易结算直接影响到天然气公司的经济效益,围绕如何加强计量管理、快速降低供销差,从工商业流量表入手是最快捷、直接有效的手段和方法。基于已有的流量表采集远传系统作为数据分析的基础,可快速诊断和定位异常流量表,实时监控用户用气,精准分析用户用气情况和用气特点,有效掌握用户用气规律,通过大数据分析发现偷盗气用户嫌疑,加强工商业用户计量治理,将流量表管理工作做到实处,实现降低供销差的目的。

Improving the Shape Accuracy by Simulating the Short-Stroke Honing Process

This study represents an approach to investigate a force controlled short-stroke honing process and especially the dependency between the type of finishing tool and the resulting shape accuracy. Based on a finite element analysis and a validation with special pressure measurement films, the contact mechanisms between the finishing tool and the workpiece are analyzed. In order to achieve a high surface quality without reducing the shape accuracy, the influence of different finishing tools with an individual material behavior on the resulting shape accuracy have been analyzed. With a variation of the geometry of the finishing tool as well as of the workpiece, different loading cases between the tool and the workpiece are considered in the finite element simulation. These results, combined with experimental investigations with different finishing films lead to an improvement of the surface quality without reducing the shape accuracy.

Seismic hazard mitigation for nuclear power plant

The seismic safety of nuclear power plan(tNPP)has always been a major consideration in the site selection,design,operation,and more recently recertification of existing installations. In addition to the actual NPP and all their operational and safety related support systems,the storage of spent fuel in temporary or permanent storage facilities also poses a seismic risk. This seismic risk is typically assessed with state-of-the-art modeling and analytical tools that capture everything from the ground rupture or source of the earthquake to the site specific ground shaking,taking geotechnical parameters and soilfoundationstructureinteraction (SFSI) into account to the non-linear structural response of the reactor core,the containment structure,the core cooling system and the emergency cooling system(s),to support systems,piping systems and non-structural components,and finally the performance of spent fuel storage in the probabilistically determined operational basis earthquake (OBE) or the safe shutdown earthquake (SSE) scenario. The best and most meaningful validation and verification of these advanced analytical tools is in the form of full or very large scale experimental testing,designed and conducted in direct support of model and analysis tool calibration. This paper outlines the principles under which such calibration testing should be conducted and illustrates with examples the kind of testing and parameter evaluation required.

mRNA enrichment protocols determine the quantification characteristics of external RNA spike-in controls in RNA-Seq studies

RNA-Seq promises to be used in clinical settings as a gene-expression profiling tool;however,questions about its variability and biases remain and need to be addressed.Thus,RNA controls with known concentrations and sequence identities originally developed by the External RNA Control Consortium(ERCC) for microarray and qPCR platforms have recently been proposed for RNA-Seq platforms,but only with a limited number of samples.In this study,we report our analysis of RNA-Seq data from 92 ERCC controls spiked in a diverse collection of 447 RNA samples from eight ongoing studies involving five species(human,rat,mouse,chicken,and Schistosoma japonicum) and two mRNA enrichment protocols,i.e.,poly(A) and RiboZero.The entire collection of datasets consisted of 15650143175 short sequence reads,131603796(i.e.,0.84%) of which were mapped to the 92 ERCC references.The overall ERCC mapping ratio of 0.84% is close to the expected value of 1.0% when assuming a 2.0% mRNA fraction in total RNA,but showed a difference of 2.8-fold across studies and 4.3-fold among samples from the same study with one tissue type.This level of fluctuation may prevent the ERCC controls from being used for cross-sample normalization in RNA-Seq.Furthermore,we observed striking biases of quantification between poly(A) and RiboZero which are transcript-specific.For example,ERCC-00116 showed a 7.3-fold under-enrichment in poly(A) compared to RiboZero.Extra care is needed in integrative analysis of multiple datasets and technical artifacts of protocol differences should not be taken as true biological findings.

Analytical modeling of geometric errors induced by cutter runout and tool path optimization for five-axis flank machining

The cutter runout effect has significant influence on the shape of cutter swept surface and the machining surface quality. Hence,it is necessary to integrate the cutter runout effect in cutter swept surface modeling,geometric error prediction and tool path optimization for five-axis flank machining. In this paper,an envelope surface model considering cutter runout effect is first established,and geometric errors induced by runout effect are derived based on the relative motion analysis between the cutter and part in machining. In the model,the cutter runout is defined by four parameters,including inclination angle,location angle,offset value and the length of cutter axis. Then the runout parameters are integrated into the rotation surface of each cutting edge that is used to form the final cutter envelope surface for the five-axis machining process. Thus,the final resulting geometric errors of the machined surface induced by cutter runout can be obtained through computing the deviations from the nominal cutter swept surface. To reduce these errors,an iterative least square method is used to optimize the tool paths for five-axis flank machining. Finally,a validation example is given for a specific ruled surface. Results show the effectiveness and feasibility of the analytical model of geometric errors induced by cutter runout,and also show that the geometric errors can be reduced significantly using the proposed tool path planning method.