基于CENTRIST的植物叶片识别研究与实现

针对传统植物识别方法工作任务量大,效率低下,难以保证数据客观性的问题,将CENTRIST视觉特征描述符应用于植物叶片的自动识别,设计出一个基于植物叶片图像的在线自动识别系统,对叶片图像进行预处理并提取其CEN-TRIST特征,使用最近邻分类器进行分类,计算并查询网络数据库中与之最匹配的图像,能够快速识别常见的32种植物叶片,平均正确识别率达到了90%以上。系统的后台使用PHP语言实现,所有叶片图像的信息存储于网络服务器的MySQL数据库中。实验结果表明,该系统对叶片识别具有非常好的效果,而且易于实现,也方便数据扩充和用户使用。     

High hydrostatic pressure assisted degradation of patulin in fruit and vegetable juice blends

The degradation of patulin introduced into different juices then treated with high hydrostatic pressure (HHP) was evaluated. A model juice prepared from apple and spinach (AS) was studied along with commercially available apple-based beverages; Pineapple:Apple:Mint (PAM), Apple:Carrot:Beet:Lemon:Ginger (CAB) and Romaine:Celery:Cucumber:Apple:Spinach:Kale, Parsley:lemon (GJ). The extent of patulin degradation was found to be dependent on applied pressure and processing time (degradation rates ranged from 0.04 to 0.19 ppb/s). The extent of patulin degradation could also be significantly (P < 0.05) correlated with the sulfhydryl group concentration of the juice with ascorbic acid and nitrite being less significant. HHP treatment of 600 MPa for 300 s at 11 °C resulted in a 62 ppb decrease in patulin introduced into GJ juice which also contained the highest level of thiols (97 μM). The thiol concentration of the other juices ranged between 39 and 69 μM with a corresponding decrease in patulin of 43–49 ppb following the same HHP treatment. The study has illustrated that HHP can be applied as a risk management tool to control patulin in apple based beverages although the extent of mycotoxin degradation is dependent on processing conditions and composition of the juice.     

Renewable-based generation expansion under a green certificate market

Quota obligations represent a policy instrument to reduce carbon emissions and incentivize renewable-based electricity generation. This support scheme places an obligation on generating companies to comply with a quota of renewable-based production. Eligible renewable units receive one certificate for each MWh, while fossil-based generating companies must buy certificates to comply with the requirement. This paper proposes a family of generation expansion models that include both an electricity and a certificate market to investigate to which degree a given quota obligation and non-compliance penalty incentivize the capacity expansion of renewable-based generation. Two market players are considered, namely, a renewable-based generating company with null operating cost and a weather-dependent capacity factor; and a fossil-based generating company with a fixed capacity and known fuel cost function. First, a complementarity model that determines the optimal capacity of the renewable-based producer considering a perfectly competitive market is proposed. Next, market players are assumed to compete in quantities à la Cournot to maximize their profits, being the generation expansion model formulated as a mathematical problem with equilibrium constraints. The relevance of properly setting the non-compliance penalty for each level of competition to comply with a given quota obligation is quantified and discussed using an stylized example.     

A new solar based multigeneration system with hot and cold thermal storages and hydrogen production

A multigeneration system based on solar thermal energy associated with hot and cold thermal storage is designed and analyzed energetically and exergetically. The system produces electricity, a heating effect, a cooling effect, hydrogen, and dry sawdust biomass as outputs by means of organic Rankine cycles, a heat pump, two absorption chillers, an electrolyser, and a belt dryer. The intermittent behavior of the renewable energy source is addressed through the incorporation of hot and cold thermal storage systems to operate an organic Rankine cycle and provide cooling at night. The performance assessment indicates that the overall (day and night) energy and exergy efficiencies are 20.7% and 13.7%, respectively. The majority of the total exergy destruction is attributable to the sawdust belt dryer, at about 64.0%.     

A Multiplex PCR Assay for the Rapid and Sensitive Detection of Methicillin‐Resistant Staphylococcus aureus and Simultaneous Discrimination of Staphylococcus aureus from Coagulase‐Negative Staphylococci

Abstract: Methicillin‐resistant Staphylococcus aureus (MRSA) is a global health concern, which had been detected in food and food production animals. Conventional testing for detection of MRSA takes 3 to 5 d to yield complete information of the organism and its antibiotic sensitivity pattern. So, a rapid method is needed to diagnose and treat the MRSA infections. The present study focused on the development of a multiplex PCR assay for the rapid and sensitive detection of MRSA. The assay simultaneously detected 4 genes, namely, 16S rRNA of the Staphylococcus genus, femA of S. aureus, mecA that encodes methicillin resistance, and one internal control. It was rapid and yielded results within 4 h. The analytical sensitivity and specificity of the multiplex PCR assay was evaluated by comparing it with the conventional method. The analytical sensitivity of the multiplex PCR assay at the DNA level was 10 ng DNA. The analytical specificity was evaluated with 10 reference staphylococci strains and was 100%. The diagnostic evaluation of MRSA was carried out using 360 foodborne staphylococci isolates, and showed 99.1% of specificity, 96.4% of sensitivity, 97.5% of positive predictive value, and 97.3% of negative predictive value compared to the conventional method. The inclusion of an internal control in the multiplex PCR assay is important to exclude false‐negative cases. This test can be used as an effective diagnostic and surveillance tool to investigate the spread and emergence of MRSA.     

Explicit solution for normal depth of parabolic section of open channels

To obtain the normal depth of parabolic section of open channels, multiple known parameters were incorporated into a comprehensive one by transforming basic equations, and a concept of the non-dimensional normal depth was introduced. The normal depth equations were simplified into a non-dimensional iterative formula that was proved to have a high velocity of convergence. By analyzing the comprehensive parameter and dimensionless normal depth under condition of usually adopted sizes of parabolic channels and through establishing their relationship, the iterative initial value of normal depth was obtained. The normal depth of parabolic channels was acquired by substituting the initial value into the iteration formula. The error analysis was made and a case study was provided as an application example. The case study showed that the iteration formula was very simple, convenient and precise for determining the normal depth of parabolic channels with the maximum relative error of normal depth being less than 0.34% when the ratio of width to depth was between 0.2 and 20.     

Formal modeling and verification of fractional order linear systems

This paper presents a formalization of a fractional order linear system in a higher-order logic (HOL) theorem proving system. Based on the formalization of the Grünwald–Letnikov (GL) definition, we formally specify and verify the linear and superposition properties of fractional order systems. The proof provides a rigor and solid underpinnings for verifying concrete fractional order linear control systems. Our implementation in HOL demonstrates the effectiveness of our approach in practical applications.     

响应面优化草石蚕多糖提取工艺研究

以草石蚕为原料，研究了草石蚕中多糖提取的工艺条件。在单因素试验基础上，通过响应面试验优化了草石蚕中多糖提取的工艺条件。结果表明，草石蚕中多糖的最佳提取工艺条件为：提取温度79．00℃，提取时间2．82h，乙醇体积浓度81．22％，料液比1g：18．49mL，此条件下草石蚕多糖提取率4．89％。     

Chinese red pepper (Zanthoxylum bungeanum Maxim.) leaf extract as natural antioxidants in salted silver carp (Hypophthalmichthys molitrix) in dorsal and ventral muscles during processing

Chinese red pepper (Zanthoxylum bungeanum Maxim.) leaf (ZML) extract contains high amounts of phenolic compounds possessing high total antioxidant capacity and hydroxyl, 1, 1-dipheny-2-picrylhydrazyl (DPPH) free radical scavenging activity. ZML extract was investigated as a natural antioxidant for the lipid stability of salted silver carp (Hypophthalmichthys molitrix) throughout salting and drying. Both dorsal and ventral muscles were examined for differences in moisture content, salt content, total lipid content, and degree of lipid oxidation. The hexanal content, Thiobarbituric acid reactive substances (TBARS) value, and lipoxygenase (LOX) activity in the ventral muscle were significantly higher than those of the dorsal muscle (p < 0.05). In the treatments with ZML extract, the hexanal content, the TBARS value, and the LOX activity were significantly lower (p < 0.05) during processing both in the dorsal and ventral muscles. The sensory qualities of processed salted fish could be improved with the amount of 0.030% extract in the dorsal muscle and 0.045% extract in the ventral muscle. These results showed that ZML extract can be a source of natural antioxidants and used as a food additive.