水煎苦参废渣中苦参碱的提取工艺研究

运用正交实验L9(34)研究了水煎苦参提取苦参碱,以及利用超声强化乙醇法提取苦参废渣中苦参碱的最佳工艺,并对两种方法的提取效果进行了比较。研究表明,水煎苦参碱提取量可达26.35mg/g苦参粉,超声强化乙醇提取法提取量可达5.632mg/g苦参渣,即超声醇的二次提取量可以达到一次水提取量的21.37%,因此可有效减少苦参碱资源浪费。     

煤矿井下爆破拒爆的主要原因及预防

综合分析煤矿井下爆破作业中产生拒爆的主要原因,并根据《煤矿安全规程》和《工种操作规程》提出了预防拒爆的措施以及正确处理拒爆的方法。     

在左半平面收敛的Dirichlet级数与随机Dirichlet级数的下级与准确下级

对于在左半平面σ〈０内收的下侧Ｄｉｒｉｃｈｌｅｔ级数所定义的解析函数ｆ１（ｓ）定义了下级;通过引入一个较弱的指数条件,建立了ｆ１（ｓ）的下级存在的充分必要条件;定义了在概率空间（Ω,Ａ,Ｐ）上的下侧随机Ｄｉｒｉｃｈｌｅｔ级数,研究了该级数所定义的随机解析函数ｆ１（ｓ,ω）的下级存在的条件;建立ｆ１（ｓ）或ｆ１（ｓ,ω）在σ〈０内的准确下级和下型概念及其与ｆ（１）ｓ或ｆ１（ｓ,ω）的系数及指数之间的     

PRESTORAGE MOISTURE CONTENT AFFECTS COLOR LOSS OF GROUND PAPRIKA (Capsicum annuum L.) UNDER STORAGE

Ground paprika samples from cultivars ‘B-18’; and ‘NuMex Sweet’; were adjusted to different prestorage moisture contents and stored under ambient temperature (19C–24C) and humidity (24–42%). Moisture content, water activity, extractable color, and surface color were determined before storage and then monthly for four months. Prestorage moisture contents equilibrated during storage. At the end of the storage period all samples had about 10% moisture content. Samples with 6% or 9% prestorage moisture content had 92% and 90% extractable color loss, respectively, for ‘B-18’; paprika and 84% and 83% color loss for ‘NuMex Sweet’; paprika, respectively. In contrast, samples stored at higher moisture contents had less color loss. Color loss after four months storage was 53% and 32% for ‘B-18’; and 51% and 30% for ‘NuMex Sweet’; at 15% and 18% prestorage moisture contents, respectively. Surface color was also affected by moisture content.     

PROLONGING THE SHELF-LIFE OF FRESH GREEN CHILE PEPPERS THROUGH MODIFIED ATMOSPHERE PACKAGING AND LOW TEMPERATURE STORAGE

The postharvest quality of green chile fruit was compared after storage in 3 types of packages at 2 temperatures (24C and 8C). Package types were corrugated cardboard boxes, pressed cardboard trays overwrapped with VF-71 polyethylene, or low-density polyethylene (LDPE) bags. Fruit packaged in boxes or overwrapped trays had 24.8% and 10.1% weight loss, respectively, after 1 week of storage at 24C. Fruit packaged in polyethylene bags lost 0.3% weight and remained green. After 1 week at 8C, the weight losses were 3.8%, 1.8% and 0% for the boxed, overwrapped and bagged treatments, respectively. Postharvest quality was maintained up to 4 weeks when fruit were packaged in LDPE bags and stored at 8C. In a second study, steady state O₂ and CO₂ levels were determined inside the LDPE packages as fruit weight and temperature were varied. Storage temperatures were 24C, 16C and 8C. At 8C, steady state O₂ levels ranged from 12.0 kPa to 0.9 kPa, and CO₂ levels ranged from 2.0 kPa to 4.6 kPa as fruit weight was increased from 120 to 480 g. At 24C and 16C, fruit packaged in 480 g units had slower ripening rates than fruit packaged in smaller units; however, fruit stored at 8C remained green the longest, regardless of fruit weight.     

低温漂巨磁阻抗磁敏开关的设计

Fe73.5Cu1Nb3Si13.5B9非晶合金薄带在540℃下17.8 MPa拉应力退火后具有宽平台和陡峻下降沿的巨磁阻抗特性,据此研制了一款新型磁敏开关。文中介绍了磁敏材料的GMI特性及磁敏开关的电路设计原理,对磁敏开关的磁场和温度特性进行了测试,结果表明:该磁敏开关的重复性好,迟滞误差小,温漂低。     

k-Dimensional hashing scheme for hard disk integrity verification in computer forensics

Verifying the integrity of a hard disk is an important concern in computer forensics,as the law enforcement party needs to confirm that the data inside the hard disk have not been modified during the investigation.A typical approach is to compute a single chained hash value of all sectors in a specific order.However,this technique loses the integrity of all other sectors even if only one of the sectors becomes a bad sector occasionally or is modified intentionally.In this paper we propose a k-dimensional hashing scheme,kD for short,to distribute sectors into a kD space,and to calculate multiple hash values for sectors in k dimensions as integrity evidence.Since the integrity of the sectors can be verified depending on any hash value calculated using the sectors,the probability to verify the integrity of unchanged sectors can be high even with bad/modified sectors in the hard disk.We show how to efficiently implement this kD hashing scheme such that the storage of hash values can be reduced while increasing the chance of an unaffected sector to be verified successfully.Experimental results of a 3D scheme show that both the time for computing the hash values and the storage for the hash values are reasonable.     

机械结构的理论及试验模态分析方法

本文主要介绍了理论和试验模态分析的建模方式、分析方法以及应用过程。讨论了分析方法的适用条件及为提高模态分析精度需要解决的问题。并以悬臂梁为例,使用DASP软件验证了模型的一致性及方法的可靠性;该理论分析及应用过程对促进模态分析法的工程应用具有重要意义。     

ICP-MS法测定镝铁合金中钨的测量结果的不确定度评定

研究了ICP-Ms法测定镝铁合金中钨的测量不确定度的影响因素，对各不确定分量进行了分析和计算。镝铁合金中W的质量分数为97.5μg／g时，测量结果的扩展不确定度为7.9μg／g。     

Privacy-preserving edge-assisted image retrieval and classification in IoT

Internet of Things (IoT) has drawn much attention in recent years. However, the image data captured by IoT terminal devices are closely related to users’ personal information, which are sensitive and should be protected. Though traditional privacy-preserving outsourced computing solutions such as homomorphic cryptographic primitives can support privacy-preserving computing, they consume a significant amount of computation and storage resources. Thus, it becomes a heavy burden on IoT terminal devices with limited resources. In order to reduce the resource consumption of terminal device, we propose an edge-assisted privacy-preserving outsourced computing framework for image processing, including image retrieval and classification. The edge nodes cooperate with the terminal device to protect data and support privacy-preserving computing on the semitrusted cloud server. Under this framework, edge-assisted privacy-preserving image retrieval and classification schemes are proposed in this paper. The security analysis and performance evaluation show that the proposed schemes greatly reduce the computational, communication and storage burden of IoT terminal device while ensuring image data security.