月饼生产、销售系统开发中BOM结构模型的研究及应用

BOM是ERP系统中重要的基本数据.文章首先从数据库设计和算法实现两方面分析了两种典型的BOM结构模型,总结出两种BOM设计中的优缺点,举列说明月饼生产、销售系统开发中BOM结构模型的应用.     

An approach to a Z toolkit for the Reference Model of Open Distributed Processing

We discuss the usage of the (non-OO) Z specification language to represent some fundamental concepts of the ISO Reference Model of Open Distributed Processing (RM-ODP) and the ISO General Relationship Model (GRM). After discussing some of the difficulties involved, we offer suggestions on how Z can be used successfully for specifying and modeling open object-based distributed systems. Although fundamental specification concepts of RM-ODP and GRM are less well-known than “traditional” mathematics, we propose an RM-ODP toolkit somewhat analogous in its usage to the well-known mathematical toolkit in Z.     

Computation of the exact Cramer–Rao lower bound for the parameters of a nonsymmetric half-plane 2-D ARMA model

The Cramer–Rao lower bound (CRLB) that gives the minimal achievable variance/standard deviation for any unbiased estimator offers a useful tool for an assessment of the consistency of parameter estimation techniques. In this paper, a closed-form expression for the computation of the exact CRLB on unbiased estimates of the parameters of a two-dimensional (2-D) autoregressive moving average (ARMA) model with a nonsymmetric half-plane (NSHP) region of support is developed. The proposed formulation is mainly based on a matrix representation of 2-D real-valued discrete and homogeneous random field characterized by the NSHP ARMA model. Assuming that the random field is Gaussian, the covariance matrix of the NSHP ARMA random field is first expressed in terms of the model parameters. Then, using this matrix structure, a closed-form expression of the exact Fisher information matrix required for the CRLB computation of the NSHP ARMA model parameters is developed. Finally, the main formulas derived for the NSHP ARMA model are rearranged for its autoregressive and moving average counterparts, separately. Numerical simulations are included to demonstrate the behavior of the derived CRLB formulas.     

Advancements in the design and validation of an air pollution integrated assessment model for Spain

This paper describes the design and application of the Atmospheric Evaluation and Research Integrated model for Spain (AERIS). Currently, AERIS can provide concentration profiles of NO₂, O₃, SO₂, NH₃, PM, as a response to emission variations of relevant sectors in Spain. Results are calculated using transfer matrices based on an air quality modelling system (AQMS) composed by the WRF (meteorology), SMOKE (emissions) and CMAQ (atmospheric-chemical processes) models. The AERIS outputs were statistically tested against the conventional AQMS and observations, revealing a good agreement in both cases. At the moment, integrated assessment in AERIS focuses only on the link between emissions and concentrations. The quantification of deposition, impacts (health, ecosystems) and costs will be introduced in the future. In conclusion, the main asset of AERIS is its accuracy in predicting air quality outcomes for different scenarios through a simple yet robust modelling framework, avoiding complex programming and long computing times.