基于腐损程度的季节性产品动态定价与订单量的集成优化(英文)

为了对易腐季节性产品的销售价格和订单量进行最优决策,考虑产品在不同腐损程度的情形下,需求与价格和时间同时相关的一类季节性产品的动态定价和订单量的集成优化问题.建立该类产品的价格制订次数、每次制订的价格和订单量的集成优化模型,并对模型进行求解,最后结合数例验证模型的实用性和可操作性,并分析产品腐损程度对价格制订次数、价格大小、订单量和利润的影响.结果表明,随着产品腐损程度的提高,零售商在销售季节内的产品价格最优制订次数保持不变;零售商在销售季节内所制订的最优价格逐渐微降;产品的最优订单量和所产生的最优利润逐渐微升.

牙齿腐损与胃肠紊乱

牙齿腐损是口颌系统的常见损害,病因多样。本文就牙齿腐损的病因、诊断标准、评分指标,牙齿腐损与胃肠紊乱的关系进行综述。

埋地金属管道腐损状况的检测与安全性评估

随着社会发展建设的不断完善,我国经济建设实现了快步走的发展目标。在经济建设和社会建设高速发展的要求下,我国各领域中的各项事业发展都要保证有条不紊的进行。然而在自然界中,被埋在地下的金属管道腐蚀情况的发生,却导致了我国工程失效的情况频频发生。本文就针对检测埋地金属管道腐蚀损坏情况的检测技术,进行了阐述。并对埋地金属管道腐蚀损坏情况进行了安全性的评估。为我国未来地下管道工程的开展,提供了一定意义上的参考价值。

碳酸饮料腐损齿质

《英国牙科杂志》发表的一份研究报告称，喝碳酸饮料会令12岁青少年齿质腐损的几率增加59％，令14岁青少年齿质腐损的几率增加220％。如果每天喝4杯以上的碳酸饮料，这两个年龄阶段的孩子齿质腐损的可能性将分别增加252％和513％。

果蔬冷藏损伤及其生理机制与对策研究

随着我国果蔬冷链储运率的提高,果蔬产业对由冷藏损伤引起的采后损失越来越重视。揭示果蔬冷藏损伤发生发展的机制,开发出相应的防控技术措施,对保证果蔬产业的丰产丰收、减损增收,促进产业可持续发展有重要意义。基于国内外研究进展,对果蔬采后冷藏损伤发生的机理进行综述,对防止果蔬采后冷藏损伤的现有技术措施进行分析探讨。

复合材料磨损破坏行为研究和发展

复合材料的耐磨损性能优于金属材料,但是在一些特殊环境下,复合材料还是会发生磨损破坏,比如材料在溶液中长期浸泡而发生的腐蚀、空泡冲击形成的侵蚀、砂石冲刷造成的磨损等,材料磨损破坏造成的后果严重,国内外学者对复合材料的磨损破坏行为和机理做了相关研究,为改善材料进而避免材料发生磨损提供了理论基础。

农产品产地冷链物流技术与应用

农产品产地冷链物流技术应用于农产品产后预冷、分级、包装、仓储等诸多环节,是实现农产品保鲜,腐损率降低和物流作业效率提升的重要手段与保障。随着农村电商的兴起,农产品产地冷链物流发展愈发受到重视,更多先进技术迎来更加广泛的应用,但整体来看,产地冷链物流仍有待持续升级。

Corrosion and tribocorrosion behaviors of AISI 316 stainless steel and Ti6Al4V alloys in artificial seawater

The corrosion and tribocorrosion behaviors of AISI 316 stainless steel and Ti6Al4V alloys sliding against Al2O3 in artificial seawater using a pin-on-disk test rig were investigated. And the synergistic effect between corrosion and wear was emphatically evaluated. The results show that the open circuit potentials of both alloys drop down to more negative value due to friction. The corrosion current densities obtained under tribocorrosion condition are much higher than those under corrosion-only condition. Friction obviously accelerates the corrosion of the alloys. The wear loss for both alloys is larger in seawater than that in pure water. Wear loss is obviously accelerated by corrosion. And AISI 316 stainless steel is less resistant to sliding damage than Ti6Al4V alloy. The synergistic effect between wear and corrosion is a significant factor for the materials loss in tribocorrosion. In this surface-on-surface contact geometry friction system, the material loss is large but the ratio of wear-accelerated-corrosion to the total wear loss is very low.

Corrosion wear synergistic behavior of Hastelloy C276 alloy in artificial seawater

A systematic investigation was carried out to discuss the corrosion and tribocorrosion behaviors of Hastelloy C276 alloy sliding against Al2O3 pin in artificial seawater, using a pin-on-disk tribometer integrated with a potentiostat for electrochemical control. The results show that the great decrease of open circuit potential and three orders of magnitude increase of corrosion current density occur caused by friction. There are clearly synergistic effect between corrosion and wear, resulting in corrosion-induced-wear and wear-induced-corrosion in tribocorrosion process. The contribution of pure mechanical wear to total material loss exceeds 70% in all sliding conditions, so mechanical wear is the dominant factor during tribocorrosion. For considering synergistic effect between corrosion and wear, the contribution of wear-induced-corrosion to total material loss is not very high although corrosion rate is greatly accelerated by friction. The fraction of corrosion-induced-wear to the total material loss is high and in the range of 14.6%-20.5% under all sliding conditions.

Effect of electrochemical state on corrosion-wear behaviors of TC4 alloy in artificial seawater

The electrochemical and corrosion?wear behaviors of TC4 alloy in artificial seawater were studied. And the influences of electrochemical state on passive behavior, failure mechanism of passive film and corrosion?wear synergy were emphatically analyzed. The corrosion?wear analysis of the alloy was fulfilled by methods of mass loss, electrochemical testing and scanning electron microscope (SEM). It can be observed that the cathodic shift of open circuit potential and three order of magnitude increase of current density can be obtained during corrosion?wear process. Total corrosion?wear loss increases with increasing applied potential, confirming the synergy between wear and corrosion. High polarisation potential results in low coefficient of friction and high corrosion rate. The relative contribution of pure mechanical wear to total material loss deceases obviously with the increase of potential from open circuit potential to 0.9 V during corrosion?wear. Contributions of wear-induced-corrosion and corrosion-induced-wear are significant especially at higher potentials.

Review on corrosion-wear resistance performance of materials in molten aluminum and its alloys

The failure caused by the corrosion-wear of molten aluminum and its alloys is one of the main problems in aluminum industry. In this work, the resistance behavior of various materials, including Fe-based alloys, ceramics and corresponding high apparatus of corrosion-wear in molten aluminum and its alloys, were reviewed. The synergistic effect of corrosion and wear was discussed based on corrosion and wear mechanics. The effects of dynamic agitation due to rotating of friction pairs, physical property of liquid metal and size of grain etc., on the corrosion-wear resistance performance were investigated. In addition, the characteristics of corrosion-wear resistance performance of materials in molten aluminum and its alloy were summarized. According to our recent progress referred to kinds of materials, especially a TiA13/Ti3A1C2/A1203 composite, the ceramics/metal composites with a co-continuous structure will be of great advantage in the field of corrosion-wear environment of molten aluminum and its alloys.

Tribocorrosion behaviors of Ti-6Al-4V and Monel K500 alloys sliding against 316 stainless steel in artificial seawater

The tribocorrosion behaviors of Ti-6Al-4V and Monel K500 alloys sliding against 316 stainless steel were investigated using a ring-on-block test rig in both artificial seawater and distilled water. It is found that friction coefficients are in general larger in distilled water compared with seawater. The wear losses of Ti-6Al-4V and Monel K500 alloys are larger in seawater compared with distilled water. The mechanical action can destroy the passive film and increase the corrosion rate. The synergism effect between corrosion and wear occurs. The synergism action between corrosion and wear is related to the corrosion rate and with the increase of corrosion rate, the synergism becomes more important. 316 stainless steel suffers severe wear sliding against Monel K500 alloy compared with sliding against Ti-6Al-4V alloy in both distilled water and seawater.

An Improved Angle Polishing Method for Measuring Subsurface Damage in Silicon Wafers

We present an improved angle polishing method in which the end of the cover slice near the glue layer is beveled into a thin,defect-free wedge,the straight edge of which is used as the datum for measuring the depth of subsurface damage. The bevel angle can be calculated from the interference fringes formed in the wedge. The minimum depth of the subsurface damage that can be measured by this method is a few hundred nanometers. Our results show that the method is straightforward, accurate, and convenient.

Wear and corrosion resistant coatings on surface of cast A356 aluminum alloy by plasma electrolytic oxidation in moderately concentrated aluminate electrolytes

Plasma electrolytic oxidation of a cast A356 aluminum alloy was carried out in aluminate electrolytes to develop wear and corrosion resistant coatings. Different concentrations of 2, 16 and 24 g/L NaAlO2 solutions and a silicate electrolyte （for comparison） were employed for the investigation. Wear performance and corrosion resistance of the coatings were evaluated by WC （tungsten carbide） ball-on-flat dry sliding tests and electrochemical methods, respectively. The results show that the coating formed for a short duration of 480 s in 24 g/L NaAlO2 solution generated the best protection. The coating sustained 30 N load for sliding time of 1800 s, showing very low wear rate of -4.5×10^-7 mm3/（N· m）. A low corrosion current density of -8.81×10^-9 A/cm2 was also recorded. Despite low α-Al2O3 content of the coating, the compact and nearly single layer nature of the coating guaranteed the excellent performances.

浅谈柴油机湿式气缸套异常失效及预防

柴油发动机湿式气缸套在使用过程中,因制造、使用维护不当,经常出现气缸套外壁穴蚀、穿孔及内壁异常磨损等现象,特别是穴蚀已成为气缸套早期失效的主要原因。笔者根据使用维修得到的经验谈点看法。 一、气缸套外壁穴蚀的特点及原因 气缸套穴蚀一般发生在承受主、次推力面一侧的气缸套中、下部,水套狭窄的高温死角处,进水口、水流转弯处,以及气缸密封圈上缘。

Antisepsis and Fresh-keeping Effects of Natamycin Coating Compounds Treatment on Red Global Grape

The aim was to research fresh-keeping effects of natamycin on cold-pre- served grape. Red globe grapes were processed with compound coating liquid of chitosan with mass fraction at 1% and natamycin with mass fractions at 0.20% （T1）, 0.40% （T2） and 0.60% （T3）, respectively. Grapes processed with water （CK3） and 1% chitosan （CK2） were taken as control groups. Rotten rate, seed shattering rate, mass loss rate, respiratory intensity and related physiological quality in test and control groups were compared. The results indicated that respiratory intensity, mass loss rate, rotten rate and seed shattering rate in CK1 were all higher than those in CK2. In addition, T1, T2 and T3 were lower in the indices than CK1 and CK2, but still kept at a high level in fruit hardness. Furthermore, mass fractions of Vc and titratable acid declined more slowly in T1, T2 and T3, compared with CK1 and CK2. Natamycin better preserved grapes and prolonged storage period. In general, natamycin with mass fraction at 0.4% proved best in fresh-keeping.

Corrosion and wear behaviors of PVD CrN and CrSiN coatings in seawater

To improve the tribological performance of 316 L in seawater, the CrN and CrSiN coatings were deposited by multi-arc ion plating. The coatings were systematically characterized. Corrosion properties were evaluated by immersion test and anodic polarization measurement. The friction and wear properties of the CrN and CrSiN coatings were investigated by ball-on-disk tribometer in artificial seawater. The results show that the CrN coating has strong（111） and（200） preferred orientations and the intensity of the peaks decreases for the CrSiN coating. The hardness of the CrSiN coating is higher than that of the CrN coating. The CrSiN coating presents better corrosion resistance in seawater. The friction coefficient and wear rate of the CrSiN coating are lower than those of the CrN coating, indicating positive effect of Si addition on tribological performance in seawater. The coatings could significantly improve the wear resistance of the 316 L in seawater.

Recent advances in energy efficient PEO processing of aluminium alloys

Plasma electrolytic oxidation(PEO)coatings developed under voltage-controlled mode on various commercial wrought,gravity cast and rheocast aluminium alloys were discussed with respect to enhancement of their tribological and corrosionperformance and minimization of the PEO energy consumption.It is demonstrated that use of conventional porous anodic filmprecursors reduces the PEO energy consumption by up to50%.The wear of6082alloy with PEO coatings with addedα-Al2O3particles is two times lower compared with electrolytic hard chrome.The long-term corrosion resistance of the PEO-coatedA356rheocast alloy is enhanced via use of a precursor and hydrophobic post-treatment.