VPI-FP: an integrative information system for factory planning

Nowadays, one of the main challenges in factory planning is the consistent and coherent information modelling along planning processes. Despite the current efforts in the fields of virtual production as well as digital and virtual factory, planning and simulation applications mostly support only the analysis and the optimisation of single planning aspects. However, to match nowadays challenges, planners require solutions that provide an integrated view to evaluate planning scenarios in advance and to achieve increasing production quality and efficiency. The concept of virtual production intelligence (VPI) provides a basic concept for such an integrative information system that enables planners to integrate, to aggregate and to analyse data gathered during one planning project as well as to compare different projects. In this study, we present such an information system for factory planning using the concept of the VPI. The focus lies in particular on the information modelling as well as the information integration and evaluation. Therefore, the study presents theoretical basics and implementations of the VPI platform within a precise application scenario in factory planning. This is to process and provide a consolidated information base along the whole planning process to support factory planning projects.     

加工高镍材料工件的刀具选用

高镍材料不会因为切削时产生高温而发生软化,因此在切削刃上会形成很高的压力。这样就可能引起刀刃因碎裂或变形而损坏。由于在切屑过程中,更强的材料产生更多的热,且导热性较低,因此形成高切削温度。大大增加了切削难度。     

Reliability and maintainability analysis to improve the operation of the limoncello production line

The reliability, maintainability, failure rate and repair rate models of a limoncello automated production line for a period of 8 months at machine and entire line level were carried out. It was pointed out that (i) the real operating time of the limoncello production line (LPL) is 89.35%, whereas for the rest 10.65%, the LPL is under repair, (ii) the Weibull distribution provided the best fit of the failure data for the LPL to describe the time‐between‐failures (TBFs), whereas the time‐to‐repairs (TTRs) are lognormal distributed, and (iii) the failure rate of the production line increases, implying that the current maintenance strategy is not adequate and must be improved. This particular methodology can also be utilised in the beverage industry sector by the machinery manufacturers and the manufacturers of bottled products to improve the design and operation management of the bottling production line.     

Entropy generation from hydrogen production of catalytic partial oxidation of methane with excess enthalpy recovery

Catalytic partial oxidation of methane (CPOM) is an important route for producing hydrogen and it is featured by autothermal reaction. To recognize the reaction characteristics of CPOM, H₂ production and entropy generation from CPOM in Swiss-roll reactors are studied numerically. The considered parameters affecting the performance of CPOM include the excess enthalpy recovery, gas hourly space velocity (GHSV), number of turns and atomic O/C ratio. The impact of chemical reactions, heat transfer and friction on entropy generation is also analyzed. The results indicate that preheating reactants through waste heat recovery as well as increasing GHSV or number of turns is conducive to enhancing H₂ yield, whereas the maximum H₂ yield develops at O/C = 1.2. A higher H₂ yield is always accompanied by a higher value of entropy generation, and chemical reactions are the main source of entropy generation, especially from steam methane reforming. In contrast, viscous dissipation almost plays no part on entropy generation, compared to heat transfer and chemical reactions. From the analysis of entropy generation, detailed mechanisms of H₂ production from CPOM can be figured out.     

The effect of fertilizer nitrogen input to grass-clover swards and calving date on the productivity of pasture-based dairy production

The objective of this systems-scale study was to investigate grazing season timeframes on pasture and milk production and on milk processability of dairy systems with compact spring-calving dairy cows grazing white clover (Trifolium repens L.) based grassland. Fifty-four primiparous and multiparous Holstein-Friesian dairy cows were used in a one-factor study with 3 systems (n = 18) and repeated over 2 yr (2008/09 and 2009/10). The 3 systems were: early spring calving with annual fertilizer N input of 100 kg·ha^?1 applied in spring (ES100N; 2.1 cows·ha^?1; grazing February to November), early spring calving without fertilizer N (ES0N; 1.6 cows·ha^?1; grazing February to November) and late spring calving without fertilizer N (LS0N; 1.53 cows·ha^?1; grazing April to January). Annual pasture production was affected by an interaction between grazing system and year: Mean annual pasture yields for 2008 and 2009 were ES100N; 10.35 and 9.88, ES0N; 8.88 and 8.63, LS0N; 9.18 and 10.31 t of dry matter (DM)·ha^?1 (SEM 0.39). LS0N had higher pasture DM yield in 2009 due to higher clover DM production and biological N fixation compared with the other systems. Clover stolon and root mass in the following February was correlated with stolon and root mass in the previous November with 64% of stolon mass present on LS0N in February (R² = 0.84). There were no detectable differences in per-lactation milk yield (6,335 kg·cow^?1), fat, protein and lactose yields (271, 226, 297 kg·cow^?1, respectively), cow liveweight (585 kg) or body condition score (3.02). Although winter grazing favored subsequent clover DM production, biological N fixation and pasture DM production, delaying calving date in spring and extending lactation into the following winter led to inefficient use of this pasture by the grazing herd and lowered the quality of late-lactation milk for processing purposes. Hence, a mean calving date in mid- to late-February is recommended for zero-fertilizer N input clover-based grassland.     

Dynamic modelling of a solar hydrogen system for power and ammonia production

A new configuration of solar energy-driven integrated system for ammonia synthesis and power generation is proposed in this study. A detailed dynamic analysis is conducted on the designed system to investigate its performance under different radiation intensities. The solar heliostat field is integrated to generate steam that is provided to the steam Rankine cycle for power generation. The significant amount of power produced is fed to the PEM electrolyser for hydrogen production after covering the system requirements. A pressure swing adsorption system is integrated with the system that separates nitrogen from the air. The produced hydrogen and nitrogen are employed to the cascaded ammonia production system to establish increased fractional conversions. Numerous parametric studies are conducted to investigate the significant parameters namely; incoming beam irradiance, power production using steam Rankine cycle, hydrogen and ammonia production and power production using TEGs and ORC. The maximum hydrogen and ammonia production flowrates are revealed in June for 17th hour as 5.85 mol/s and 1.38 mol/s and the maximum energetic and exergetic efficiencies are depicted by the month of November as 25.4% and 28.6% respectively. Moreover, the key findings using the comprehensive dynamic analysis are presented and discussed.     

CME Forum: a response to “Construction flow index: a metric of production flow quality in construction”

The study of types of flow in construction is a relatively new field. This paper reviews the work of Sacks et al. and reveals that they have applied a production-line metaphor with recognition of two production flows. Process flow: locations are equated with products moving down a production line. Operations flow: work crews are equated to work stations. Their work proposes an index of the quality of production flow in construction, but the research design has three significant flaws: the skilled interpretation of flow-line charts is not in turn applied to the interpretation of their example charts; the conceptual framework does recognize that the underlying metaphor requires levels of detail in both location and task that is not supported in their analysis. The meaning of “quality of flow” in this context is not defined. This debate raises important epistemological questions for those working in lean construction and location-based management. While the concept of “production flow quality” is important, the Sacks et al. methodology does not address the detailed planning of individual crews. It is only possible to apply the production-line metaphor if micro-management is adopted as detailed planning.     

Discrete-time mixed-integer programming models and solution methods for production scheduling in multistage facilities

We address the problem of production scheduling in multi-product multi-stage batch plants. Unlike most of the previous works, which propose continuous-time models, we study discrete-time mixed-integer programming models and solution methods. Specifically, we discuss two models based on network representations of the facility and develop two new models inspired by the Resource-Constrained Project Scheduling Problem. Furthermore, we propose different solution methods, including tightening methods based on processing unit availability, a reformulation based on processing unit occupancy, and an algorithm to refine approximate solutions for large-scale instances. Finally, we present a comprehensive computational study which shows that speedups of up to four orders of magnitude in are observed when our models and methods are compared to existing approaches.     

Potential for using enriched cultures and thermotolerant bacterial isolates for production of biohydrogen from oil palm sap and microbial community analysis

A limited number of bacteria can convert oil palm (Elaeis guineensis) sap to hydrogen with satisfactory yield and productivity. In this study, a total of 18 fermentative enriched cultures and 36 newly isolated thermotolerant bacterial strains were compared for hydrogen production from oil palm (OP) sap. The new isolates were obtained from hot springs, palm oil mill effluent and oil palm sap. The test was conducted in three steps: (i) a test for hydrogen production from mixed substrates (cellulose, starch, xylose, and glucose) and OP sap; (ii) a test for substrate concentration tolerance; and (iii) a test for thermotolerance. Five enriched candidates for each of the hydrogen producers were selected according to the criteria defined for the screening test. The hydrogen production of these selected bacterial strains from hot springs were cultivated in batch fermentation of oil palm sap at room temperature (30 ± 2 °C). Five enriched cultures, namely 81RN1, OPS, 85RN5, 89SR3-2 and 112YL1 were found to give high cumulative hydrogen formation of 1085, 1009, 994, 983 and 778 mL H₂/L-OP sap, respectively, with the hydrogen content of 29.8, 29.4, 28.7, 27.1 and 27.5%, respectively. PCR–DGGE profiling showed that all these five enriched cultures consisted of species closely related to the genus Clostridium sp. based on the 16S rRNA gene. For pure cultures, the top five hydrogen producers were the isolates encoded as PS-3, PS-4, PS-5, PS-7 and PS-8 exhibiting the hydrogen production of 1973, 1774, 1335, 1170 and 1070 mL H₂/L-OP sap, respectively, with the hydrogen content of 33.7, 29.6, 32.5, 31.5 and 26.4%, respectively. Identification of these high hydrogen producers using 16S rRNA sequence matching showed that the isolates PS-3 and PS-8 belonged to Clostridium beijerinckii, while the isolate PS-7 belonged to Clostridium acetobutylicum and the isolates PS-4 and PS-5 belonged to Klebsiella sp. and Klebsiella pneumoniae, respectively. Therefore, the pure culture C. beijerinckii PS-3 exhibited 1.8 folds higher hydrogen production (1973 mL H₂/L-OP sap) than the enriched cultures of 81RN1 (1085 mL H₂/L-OP sap).     

生产优质塑料异型材的十大要素

本文论述了生产门窗用优质塑料异型材的十大要素,为企业提高型材质量提供了理论依据。