带有时间窗的生鲜物流配送路径优化研究

随着生鲜消费的日益增多,生鲜物流配送也面临着如何在快速安全的条件下满足人们对生鲜的需求,使消费者在最短的时间得到最新鲜产品的现实问题,提出带有时间窗的生鲜物流配送车辆路径问题.充分考虑配送距离、车辆固定成本、生鲜损耗等多种因素,设计以配送损耗为可变成本和车辆启动费用为固定成本之和最小的优化目标,建立带有时间窗生鲜损耗的配送模型.针对模型的特征,设计自适应遗传算法求解该模型.最后,结合仿真算例来验证模型与算法的有效性.     

Modified QuEChERS method for phenolic compounds determination in mustard greens (Brassica juncea) using UHPLC-MS/MS

A modified QuEChERS method (Quick, Easy, Cheap, Effective, Rugged, and Safe) for the determination of fifteen phenolic compounds in mustard greens (Brassica juncea) using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS) analysis was developed. The QuEChERS partitioning step and dispersive solid phase extraction (d-SPE) clean-up sorbents were investigated, aimed at phenolic compound extraction and pigment removal, respectively. QuEChERS acetate version combined with 25 mg of diatomaceous earth (DE) and 5.0 mg of graphitized carbon black (GCB) provided the best conditions for sample preparation of the target compounds. Under the optimized conditions, all phenolic compounds showed good linearity (r ≥ 0.99) over the concentration range of 0.1 to 8000 μg kg⁻¹, and the quantification limits were in the range of 0.06–230 μg kg⁻¹. The spectrophotometric analysis showed that the clean-up step promoted a significant removal of chlorophyll, which is the major pigment present in the sample. Furthermore, antioxidant activity analysis was also carried out after the clean-up step and, together with chromatographic data, showed that no significant retention of the phenolic compounds occurs in the clean-up step. Two mustard greens varieties – Southern Giant Curled (SGC) and Florida Broadleaf (FB) - were analyzed with the proposed method. Seven phenolic compounds (4-hydroxybenzoic, p-coumaric, ferulic and sinapic acids, naringenin, apigenin and kaempferol) were found in both varieties, the greatest abundance being for sinapic acid (1261.5 ± 23 μg kg⁻¹ in SGC and 1235.5 ± 26 μg kg⁻¹ in FB) and ferulic acid (2861 ± 24 μg kg⁻¹ in SGC and 3204.5 ± 45 μg kg⁻¹ in FB).     

悬浮液进样-火焰原子吸收光谱法测定虾仁中的钙、镁

建立了快速测定虾仁中钙、镁含量的悬浮液进样－火焰原子吸收光谱法。将虾仁样品烘干、粉碎、过98μm筛后，制成琼脂悬浮液。以La^3 溶液作为释放剂，用工作曲线法测定虾仁样品中钙、镁的含量。钙、镁的线性范围分别为0-200μg/(25mL)、0－30μg/(25mL)，检出限分别为0.056mg/L、0.0046mg/L。测定结果的相对标准偏差不大于2.4%，测定结果与在灰化法一致，测定钙、镁的平均相对误差分别为-1.3%、-4.2%。     

Calculation of Groundwater Flows in Coastal Pressurized Reservoirs

A model of a fresh groundwater flow through a rectangular horizontal pressurized reservoir toward a salt-water sea (basin, reservoir, trench, etc.) is examined within the framework of two-dimensional steady-state flow theory. In order to study the model, a mixed multi-parameter boundary value problem of the theory of analytic functions is formulated and solved using the Polubarinova-Kochina method. The structure and the characteristic features of the simulated process and the effect of all the determining physical parameters of the model on the nature of the flow are analyzed using the analytic dependences obtained and numerical calculations. An approximate hydraulic solution of the problem is compared with the exact solution obtained.     

饱和非饱和土壤中溶质运移的数值模拟

本文结合拉格朗日观点的运动坐标与欧拉观点的固定坐标,分别求解对流—弥敌方程的对流效应和弥散效应,并在从固定坐标向运动坐标投影时利用了三次样条插值方法,使模型更为精确而简单。通过与特定情况下的理论解比较,说明模型是准确可靠的。通过与实验室室内试验结果的比较,模型的可靠性得到了进一步的验证。利用模型对淡水洗盐结合浅群井抽排咸水治理盐碱地过程的模拟分析,认为结合浅群井抽排可较大地提高淡水洗盐的效果。     

Hydrodynamic Investigation of Certain Groundwater Flows in Coastal Pressurized Aquifers

Mathematical models of certain fresh groundwater flows through a semi-infinite pressurized aquifer toward a salt-water sea (basin, reservoir, etc.) are examined within the framework of two-dimensional steady-state flow theory. In order to study the models, mixed boundary value problems of the theory of analytic functions are formulated and solved using the Polubarinova-Kochina method. Algorithms for calculating the flows are developed on the basis of these models for situations in which groundwater streams arrive at the sea from one side or from below. Both the structure and the characteristic features of the simulated processes and the effect of all the physical characteristics of the models on the nature of the flow are analyzed in detail using the exact analytic dependences obtained and numerical calculations. The calculation results for the two inflow schemes are compared and features of the flows that depend on the initial position of the fluid contact are discussed.     

基于时间可控和随机损失的生鲜农产品供应链协调

生鲜农产品不仅是易腐的,其寿命还具有随机性,在订货和由产地运往远方销地的过程中,面临随机供给与需求的匹配、变质损失与物流成本的平衡这两重难题。基于现代物流条件下物流时间的可控性,分别建立了分散控制和集中控制供应链的决策模型,分析得到了它们的最优订货量和最优物流时间。在此基础上,设计了一组联合契约,推导出了实现生鲜农产品供应链协调时契约参数取值范围的计算公式。研究结果表明:通过选择合理的契约参数φ,联合契约能够完美协调生鲜农产品供应链、实现供需双方帕累托最优。进一步,对变质率参数和需求价格弹性系数进行了敏感性分析,为生鲜农产品供应链实践提供了一些管理启示。     

时间约束下鲜活农产品供应链应急协调数量折扣契约研究

本文的目的就是针对一个由生产商和一个零售商构成的鲜活农产品供应链,在考虑损耗和新鲜度的影响下,研究数量折扣契约如何协调供应链应对突发事件。 首先,给出了正常情况下供应链协调模型;然后,在突发事件引起市场需求、零售商订货成本和产品运输时间同时扰动情况下,讨论了突发事件对集权、分权供应链的影响。 研究表明,集权供应链具有一定的鲁棒性,当突发事件造成市场需求、零售商订货成本和产品运输时间在一定范围内同时发生扰动时,其生产计划不需要调整,只需通过调整产品价格即可使集权供应链达到协调;对于分权供应链,根据三因素同时扰动的不同程度,通过调整数量折扣契约参数,可以实现对供应链的协调。 最后给出数值算例验证了相关结论。     

产凝乳酶乳酸菌的筛选及其在鲜奶酪中的应用

实验以脱脂乳为原料, 从20株源于新疆传统酸奶的乳酸菌中筛选出3株高产凝乳酶的乳酸菌. 以凝乳活性最高的菌株组合为发酵剂, 通过单因素及响应面实验, 优化鲜奶酪发酵的接种量、发酵时间、后熟时间. 结果表明, 以植物乳杆菌RC5为发酵剂, 其最适发酵工艺为: 接种量5%, 38℃发酵时间14.5h, 4℃后熟时间60min. 在该条件下发酵成的鲜奶酪凝乳效果好, 色泽均匀, 奶味浓郁, 口感细腻, 为以乳酸菌产凝乳酶代替凝乳酶粉的研究和应用提供基础.     

Evaluation of Hepatoprotective Activity and Oxidative Stress Reduction of Rosmarinus officinalis L. Shoots Tincture in Rats with Experimentally Induced Hepatotoxicity

Rosmarinus officinalis L. is a widely known species for its medicinal uses, that is also used as raw material for the food and cosmetic industry. The aim of the present study was to offer a novel perspective on the medicinal product originating from this species and to test its hepatoprotective activity. The tested sample consisted in a tincture obtained from the fresh young shoots. Compounds that are evaluated for this activity are polyphenols and terpenoids, that are identified and quantified by HPLC–UV–MS and GC–MS. Antioxidant activity was assessed in vitro, using the DPPH, FRAP and SO assays. Hepatoprotective activity was tested in rats with experimentally-induced hepatotoxicity. In the chemical composition of the tincture, phenolic diterpenes (carnosic acid, carnosol, rosmanol, rosmadial) and rosmarinic acid were found to be the majority compounds, alongside with 1,8-cineole, camphene, linalool, borneol and terpineol among monoterpenes. In vitro, the tested tincture proved significant antioxidant capacity. Results of the in vivo experiment showed that hepatoprotective activity is based on an antioxidant mechanism. In this way, the present study offers a novel perspective on the medicinal uses of the species, proving significant amounts of polyphenols and terpenes in the composition of the fresh young shoots tincture, that has proved hepatoprotective activity through an antioxidant mechanism.