区块链落地食品追溯产业的制约因素分析

目的 探究区块链应用食品追溯产业的主要制约因素，帮助食品供应链参与方解决技术应用难题。方法 首先，基于11家区块链技术平台企业和3家食品企业访谈内容，通过扎根理论筛选出区块链技术应用食品追溯产业的内外部制约因素。其次，结合专家打分法和层次分析法对制约因素进行权重排序和评价分析。结果 研究表明制约因素权重评价由4个准则层和12个指标层构成。其中，指标层因素中，排名从高到低依次是：区块链投入产出（0.1430）、信源真实（0.1288）、链上企业配合意愿（0.1176）、食品企业认知度（0.0974）、标准体系（0.0942）、运作效率（0.0769）、消费者认可度（0.0733）、市场准入门槛（0.0694）、法律法规（0.0597）、人才建设（0.0594）、系统兼容（0.0470）、政策扶持（0.0333）。结论 区块链投入产出低、上链信源真实度存疑、链上企业配合意愿低、食品企业对区块链认知度低是区块链落地食品追溯产业的主要障碍，对此，应加大技术应用场景研究、提高市场认知水平、完善政策保障机制。     

海参肽饮品的加工工艺及品质分析

目的 研制海参肽饮品的加工工艺并进行饮品品质分析。方法 以鲜活刺参为原料，利用酶解与纳滤技术，获得海参肽酶解液，加入药食同源辅料研制海参肽饮品。通过单因素试验和正交试验确定产品最优配方，分别利用电子鼻和电子舌对饮品的挥发性成分和滋味进行分析。结果 海参肽饮品的最优配方为：以海参肽复配液（含桑葚粉0.3%、蓝莓粉0.3%、茉莉花1%）为基础，添加红糖3%、蜂蜜2%、山楂2%、红枣3%。饮品的挥发性成分中氮氧化物、氢化物、芳香烷烃含量较高，其酸味、苦味、涩味、鲜味、丰富味较海参酶解液有明显变化，17种氨基酸总含量为7026 mg/kg，其中谷氨酸含量可高达1100 mg/kg，微生物指标均在国家标准要求范围内。结论 海参肽饮品含有丰富的营养物质，香气组成丰富，口感佳。     

东风4D型机车车轴的超声波探伤

为了对东风4D型机车车轴进行全面的超声波检测,设计了模拟试件和缺陷,研究了超声波探伤方法以及相应的探头。该试件为1：1设计,针对机车车轴的各个应力集中点,在试轴上设计了12处模拟缺陷,作为探伤的对比缺陷当量。采用多种角度超声波探头对车轴进行全面检测,介绍了不同部位所选用斜探头的K值和小角度纵波探头的角度,并采用表面波探头检测车轴轴身,设计了双晶探头检测外侧压装线部位。通过多种类型和角度的超声波检测方法的共同作用,能够实现东风4D型机车车轴的全面检测。     

居民社区终端超市的无人配送瓶颈探究

以某大型居民社区为研究对象,通过文献研究,用户访谈,问卷分析及行为观察等方法,分析梳理社区终端超市无人配送"最后一公里"的难点及问题:企业端无人配送设备功能不能满足配送要求,未攻克技术难点,未获准社区准入权限;政府端鼓励政策及资金支持未出台,法律体系不完善;消费者端对于无人配送服务接受度较低,中老年人群学习成本高.为实...     

Membrane coagulation bioreactor (MCBR) for drinking water treatment

In this paper, a novel submerged ultrafiltration (UF) membrane coagulation bioreactor (MCBR) process was evaluated for drinking water treatment at a hydraulic retention time (HRT) as short as 0.5h. The MCBR performed well not only in the elimination of particulates and microorganisms, but also in almost complete nitrification and phosphate removal. As compared to membrane bioreactor (MBR), MCBR achieved much higher removal efficiencies of organic matter in terms of total organic carbon (TOC), permanganate index (COD(Mn)), dissolved organic carbon (DOC) and UV absorbance at 254nm (UV(254)), as well as corresponding trihalomethanes formation potential (THMFP) and haloacetic acids formation potential (HAAFP), due to polyaluminium chloride (PACl) coagulation in the bioreactor. However, the reduction of biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC) by MCBR was only 8.2% and 10.1% higher than that by MBR, indicating that biodegradable organic matter (BOM) was mainly removed through biodegradation. On the other hand, the trans-membrane pressure (TMP) of MCBR developed much lower than that of MBR, which implies that coagulation in the bioreactor could mitigate membrane fouling. It was also identified that the removal of organic matter was accomplished through the combination of three unit effects: rejection by UF, biodegradation by microorganism and coagulation by PACl. During filtration operation, a fouling layer was formed on the membranes surface of both MCBR and MBR, which functioned as a second membrane for further separating organic matter.     

一种相变材料热沉的优化设计

某些电子设备需要工作在没有空气热沉的环境条件下,如消防员使用的生命探测器等,使用普通的热设计措施,如利用器件或结构自身的热容延缓核心关键器件温度上升的做法已经越来越不适用。论文对一种相变热沉进行了参数化建模及分析,并利用Icepak和参数化分析流程结合虚拟比热法进行了计算,得出了影响某实际工程中PCM热沉效能的几个相关参数及其对应的结构相对最优值。     

Merging Nanowires and Formation Dynamics of Bottom-Up Grown InSb Nanoflakes

Indium Antimonide (InSb) is a semiconductor material with unique properties, that are suitable for studying new quantum phenomena in hybrid semiconductor-superconductor devices. The realization of such devices with defect-free InSb thin films is challenging, since InSb has a large lattice mismatch with most common insulating substrates. Here, the controlled synthesis of free-standing 2D InSb nanostructures, termed as “nanoflakes”, on a highly mismatched substrate is presented. The nanoflakes originate from the merging of pairs of InSb nanowires grown in V-groove incisions, each from a slanted and opposing {111}B facet. The relative orientation of the two nanowires within a pair, governs the nanoflake morphologies, exhibiting three distinct ones related to different grain boundary arrangements: no boundary (type-I), Σ3- (type-II), and Σ9-boundary (type-III). Low-temperature transport measurements indicate that type-III nanoflakes are of a relatively lower quality compared to type-I and type-II, based on field-effect mobility. Moreover, type-III nanoflakes exhibit a conductance dip attributed to an energy barrier pertaining to the Σ9-boundary. Type-I and type-II nanoflakes exhibit promising transport properties, suitable for quantum devices. This platform hosting nanoflakes next to nanowires and nanowire networks can be used to selectively deposit the superconductor by inter-shadowing, yielding InSb-superconductor hybrid devices with minimal post-fabrication steps.     

西伯利亚百合花药色素稳定性的研究

本文研究了东方系西伯利亚百合花药色素的稳定性。结果表明：该色素在pH=4时较稳定；对光照、温度也较稳定；Ca^2 、苯甲酸钠对其有增色作用；Na^ 、蔗糖对色素有一定的降解作用；Fe^3 、Cu^2 对该色素有明显的不良影响：VC、H2O2则有明显的破坏作用。     

Initiation and propagation behaviors of interior microflaws in the pyrolysis of an air-cured polycarbosilane precursor fiber

In the preparation of Nicalon-type Si—C—O fibers using a normal-pressure synthesized polycarbosilane precursor, a network of microflaws were detected on the cross-section of ceramic fibers obtained. Cross-section morphologies of the interior microflaws were investigated via SEM technique after certain temperature pyrolysis and their initiation and propagation behaviors were studied accordingly. The results showed that no microflaws came into being at the temperature up to 600°C due to the organic nature of the material. As a result of high weight loss and composition change, however, microflaws initiated over 600°C, formed at 700°C and propagated along the core-edge direction from 700–;900°C. Up to 1100°C, a microflaw network was formed because new microflaws generated across the oriented ones and interconnected them to form a network.     

一个演绎工程数据库语言DEL

演绎工程数据库是工程数据库和演绎数据库集成的产物,它综合了工程数据库和演绎数据库的特点,集成了演绎数据库的查询能力和工程数据库的工程数据、对象、环境建模能力,对数据库技术的不断进步和完善有重要的理论意义和实用价值.文中分析了国内外目前在相关领域的研究现状以及出现的问题,介绍了现有数据库语言的特点及不足,提出演绎工程数据库的思路,讨论了如何扩充SQL以支持在基于逻辑的工程数据库环境下操纵各种知识,保证了其语言的易用性和与原有工程数据库的结合,对演绎工程数据库语言DEL的语法及DEL SQL实现作了详细介绍,并给出了DEL SQL语言的应用实例,验证了DEL SQL语言的适用性和正确性.