发动机制造企业的成本控制与SAP

发动机因其开发周期长,科技含量高,材料材质、工艺路线复杂、环保要求高等原因,而成为高成本的制造行业。因此,有效的成本控制已是发动机制造企业在激烈的市场竞争中成败的关键。SAP系统因其数据集成性、资源共享性、传输及时性等特点,摈弃了以往发动机制造企业传统成本管控中的数据多源、信息屏蔽、权限分散等弊端,做到了研发、工艺、生产、物流、财务数据同源、资源共享、责权分担,为柴油机制造企业从产品研发源头就实施有效的成本控制提供了手段,极大地提高了企业成本管控的质量和效益。     

Precipitation of iron-rich intermetallic phases in Al-4.6Cu-0.5Fe-0.5Mn cast alloy

The solidification of Al-4.6Cu-0.5Fe-0.5Mn (206 type) cast alloy has been studied using Thermal Analysis, Differential Scanning Calorimeter, Scanning Electron Microscopy, Electron Back-Scattered Diffraction (EBSD), and Transmission Electron Microscopy (TEM). It is interesting to note that an iron-rich intermetallic phase, Al₃(FeMn), is experimentally observed to be dominantly present in the fully solidified cast structure of the experimental 206 cast alloy, in addition to β-Fe (Al₇Cu₂(FeMn)/Al₇Cu₂Fe) phase. Al₃(FeMn) phase is formed through a eutectic reaction approximately at 640 °C during solidification, possibly resulting from the phase selection and segregation of Fe in liquid Al. The presence of the Al₃(FeMn) phase has been confirmed by both EBSD and TEM. It is also found that both β-Fe and Al₆(FeMn) are possible to nucleate on Al₃(FeMn), as confirmed by the calculated low planar disregistries. The possible solidification reactions have been established for 206-type cast alloy at 0.5%Fe.     

The influence of simulation time-resolution on the matching between on-site micro-wind generation and building electric demand

This paper is to investigate the unique impact of simulation time-resolutions on energy matching between on-site micro-wind turbine and household electric demand. The focused indices are on-site electrical energy fraction (OEFe), on-site electrical energy matching (OEMe), and their errors (e_OEF and e_OEM). The methodology consists of parametric analyses with respect to time-resolution levels, averaging methods, demand profiles, turbine capacities, and wind conditions. Two averaging methods are used: ‘Speed Averaging’ and ‘Power Averaging’. With a coarser resolution, two averaging effects have been found. One is an overestimation effect by both the averaging methods, which are more likely to be encountered especially when a high-resolution generation curve frequently crosses intermittent long spikes of a demand curve. The other effect is an underestimation effect on OEFe simultaneously occurring with the Speed Averaging Method under the conditions of (1) a low wind speed and (2) a high unstable wind speed and a low turbine capacity.     

Application of Air-Assisted Liquid-Liquid Microextraction for Determination of Some Fluoroquinolones in Milk Powder and Egg Samples: Comparison with Conventional Dispersive Liquid-Liquid Microextraction

Herein, an air-assisted liquid-liquid microextraction (AALLME) has been described and compared to conventional dispersive liquid-liquid microextraction (DLLME) for the extraction/preconcentration of six fluoroquinolone compounds in milk powder and egg samples prior to high-performance liquid chromatography-UV detection (HPLC-UV). In order to compare the novel AALLME technique to the conventional DLLME technique, several parameters that influence the extraction efficiency were studied and optimized. Both methods have been validated for milk powder and egg analysis, obtaining limits of quantification lower than those usually permitted by legislation in food matrices, with precisions expressed as coefficients of variation lower than 8 % and recoveries between 72 and 115 % which were acceptable recoveries and repeatability. An AALLME method needs less organic solvent and shorter centrifugation time; therefore, it is more environmentally friendly and efficiently compared to DLLME.     

Effect of joint gap on the quality of laser beam welded near-β Ti-5553 alloy with the addition of Ti–6Al–4V filler wire

Ti–5Al–5V–5Mo–3Cr (Ti-5553) sheets were welded using a Nd: YAG laser system and Ti–6Al–4V filler wire. The effect of joint gap on weld geometry, defects, microstructure, and hardness was investigated. Fully penetrated welds up to a joint gap of 0.5 mm were produced. The two main defects observed were porosity and underfill. The addition of filler wire reduced underfill but increased porosity, especially at large joint gaps. The fusion zone (FZ) microstructure at low joint gaps consisted of retained β with a dendritic morphology. At a joint gap of 0.3 mm, regions of orthorhombic α″ martensite were observed in the weld zone which increased in proportion as the joint gap increased from a volume percentage of 4.9% at 0.3 mm to a volume percentage of 44% at 0.5 mm. Despite the differences in microstructure with increasing joint gap, the FZ hardness remained relatively constant for all joint gaps evaluated.     

Extraction of europium and electrodeposition of Al–Li–Eu alloy from Eu2O3 assisted by AlCl3 in LiCl–KCl melt

The work presents an electrochemical study on preparation of Al–Li–Eu alloys on a tungsten electrode in molten LiCl–KCl–AlCl₃–Eu₂O₃ system at 753 K and 953 K. Gibbs energy shows that AlCl₃ can chloridize Eu₂O₃, with a discharge in the form of Eu(III) ions on the cathode. The electrochemical behavior of Al(III), Li(I) and Eu(III) and alloy formation processes were investigated by cyclic voltammetry, square wave voltammetry, and chronopotentiometry. Cyclic voltammetry indicated that the underpotential deposition of europium on pre-deposited Al forms two Al–Eu intermetallic compounds at electrode potentials around ?2.00 V and ?2.34 V, respectively. And the underpotential deposition of lithium on Al surface at about ?2.24 V leads to a formation of Al–Li alloy. X-ray diffraction (XRD) indicated that Al–Li–Eu alloys with different phases were obtained via galvanostatic electrolysis. The microstructure and micro-zone chemical analysis of Al–Li–Eu alloy were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), respectively. The analysis of EDS showed that element Eu mainly distributes on needle-like precipitate, and not homogeneously in the Al–Li–Eu alloy. Composition of the alloys was analyzed by inductive coupled plasma analysis, and current efficiency was also determined with respect to the alloy composition.     

城市道路Y型交叉口渠化方法

在分析Y型交叉口成因、分类及特点的基础上,提出了Y型交叉口有别于常规交叉口的渠化原则,并从4个方面具体提出了Y型交叉口渠化的关键技术方法。最后以山东省某县城Y型交叉口渠化为例,验证了该方法的有效性。     

Perovskite ceramic oxide as an efficient electrocatalyst for nitrogen fixation

The electrochemical conversion of N₂ to NH₃ is an interesting research topic as it provided an alternative and energy-saving method compared with the traditional way of NH₃ production. Although different materials have been proposed for N₂ reduction, the use of defects in oxides was only reported recently and the relevant working mechanism was not fully revealed. In this study, Sr was used as the dopant for LaFeO₃ to create oxygen vacancies, forming the Sr-doped LFO (La_0.5Sr_0.5FeO_3-δ) perovskite oxide. The La_0.5Sr_0.5FeO_3-δ ceramic oxide used as a catalyst achieves an NH₃ yield of 11.51 μgh^?1 mg^?1 and the desirable faradic efficiency (F.E.) of 0.54% at ?0.6 V vs reversible hydrogen electrode (RHE), which surpassed that of LaFeO₃ nanoparticles. The ¹⁵N isotope labeling method was employed to prove the La_0.5Sr_0.5FeO_3-δ catalyst had the function of converting N₂ into NH₃ under the electrolysis condition. The first principle calculations were used to investigate the mechanism at the atomistic level, revealing that the free energy barriers changed significantly with the introduction of oxygen vacancies that accelerated the overall nitrogen reduction reaction (NRR) procedure.     

Pressure release characteristics of premixed hydrogen-air mixtures in an explosion venting device with a duct

The technology of explosion venting with a duct can effectively reduce the destructive effect generated from gas accidental explosion in the place of intensive industrial production, while it is not applicable to the production site designed for the technology without ducts. Since it is not clear how to quantitatively evaluate the regularity of energy release in explosion venting especially under high cracking pressure, it is still challenging on the safe application of the technology. This paper aimed to explore the basic characteristics of explosion pressure in a 20 L sphere vessel and venting duct during hydrogen explosion venting for safety design. The effects of the cracking pressure and duct length on explosion pressure at different positions were systematically analyzed according to the test of the hydrogen with different concentrations in an explosion venting device with a duct. Comparing the results of explosion pressure characteristics with experiments conducted in a device without a duct, and quantitatively analyzing the pressure release rule, manifested that the presence of the duct reduced the explosion venting efficiency to a certain extent. In the meantime, by comparing the standard NFPA 68 (P_cra ≤ 0.075 MPa, 0.1 m³ ≤ V ≤ 10,000 m³) for safety design of explosion venting devices, the extended implementation scheme with a venting duct was assessed, implying that the calculation results from NFPA 68 were relatively stable in over-scope (P_cra > 0.075 MPa, V < 0.1 m³) measurement. In future industrial productions, the design of high-pressure hydrogen venting is suggested, leaving sufficient safety margin when referring to the result.