Probabilistic fault diagnosis method based on the combination of nest-loop fisher discriminant analysis and analysis of relative changes

Bias of data location and increase in data variations are two typical disturbances, which in general, simultaneously exist in the fault process. Targeting their different characteristics, a nested-loop fisher discriminant analysis (NeLFDA) algorithm and relative changes (RC) algorithm are effectively combined for analyzing the fault characteristics. First, a prejudgment strategy is developed to evaluate the fault types and determine what changes are covered in the fault process. Two statistical indexes are defined, which conduct Monte Carlo based center fluctuation analysis and dissimilarity analysis respectively. Second, for the fault data containing those two faults simultaneously, a combined NeLFDA-RC algorithm is proposed for fault deviations modeling, which is termed as CNR-FD. Fault directions concerning bias of data location are extracted by the NeLFDA algorithm and then corresponding fault deviations are removed from the fault data. Then RC algorithm is performed on these fault data to extract directions concerning increase of data variations. These fault directions are used as reconstruction models to characterize each fault class. Particularly, the compromise between these two algorithms is determined by the Monte Carlo based center fluctuation analysis. For online applications, a probabilistic fault diagnosis strategy based on Bayes’ rule is performed to identify fault cause by discovering the right reconstruction models that can make the reconstructed monitoring statistics have the largest probabilities of belonging to normal condition. The motivation of the proposed algorithm is illustrated by a numerical case and the performance of the reconstruction models and the probabilistic fault diagnosis strategy are illustrated using pre-programmed faults from the Tennessee Eastman benchmark process and the real industrial process data from the cut-made process of cigarettes in some cigarette factory.     

Another look at the phenomenon of phase transition

This study is motivated by the question whether there exists a characteristic feature common to the phenomenon of phase transition of properties taking place in the course of evolution of various sets of objects of different nature. A novel measure model of phase transition is presented, providing an insight into the process underlying different phase transitions. First, it is shown to conform to several famous and extensively investigated cases of phase transition. Then a few close consequences of applying the measure model are presented. It has been proved that monotone properties undergo a sharp phase transition. The measure model provides a sufficient condition of a sharp phase transition common to monotone and non-monotone properties as well. The measure model reveals that if a property Q undergoes a phase transition in the course of evolution of objects of a certain type, then there exist other secondary properties related to the measure of Q that also undergo a phase transition during the evolution.     

Short‐term effects in a reduced flow stretch: The case of the Antas River in South Brazil

The building of adduction channels (penstocks) that conduct water from reservoirs to turbines, which are located kilometres from the dam, is becoming common, optimizing the electricity generation in small dams. This design creates a river stretch with reduced discharge between the dam and the powerhouse. This study evaluates the short‐term impacts of the below‐dam decrease in river flow on fish assemblages. Samples were collected in the reduced flow stretch of the Castro Alves Hydropower Plant (Antas River, Rio Grande do Sul, Brazil) before the reservoir started operating (January 2008; mean discharge of 103.7 m³/s) and immediately after operation began (March 2008; mean discharge of 12.4 m³/s). Sampling was conducted in distinct habitats of the reduced flow stretch (slow waters—gillnets, sand beaches—seining nets, structured littoral—electrofishing, and fast waters—cast nets) with a strongly standardized effort. The attributes of the fish assemblages were not negatively affected by the flow reduction in any habitat sampled. However, distinct changes in the spatial structure were observed considering the different types of habitat predominantly used by the species, which represents an entire reorganization of the fish assemblages in the short term. It is fundamental that these short‐term aspects be considered in the licensing of hydropower plants in addition to the long‐term changes.     

Development of an image evaluation method for skin color distribution in facial images and its application: Aging effects and seasonal changes of facial color distribution

In this article, we present an evaluation method for the skin color distribution in the face area. Unlike previous methods that extract a specific area, our method subdivides the entire face into small regions and analyzes detailed, per-frame textures. Our evaluation method for skin color distribution is based on facial feature points and includes segmentation that takes into account the facial skeleton and muscle orientation. The use of facial feature points enables a comparison at relatively equal positions on the face without depending on the shape or size of the individual's face. Our evaluation method is versatile, and as an application, we clarified age-specific features and seasonal variations of facial color distribution. As a result of applying this evaluation method to the facial images of women aged 20 to 78 years, we confirmed that the lightness of the face decreased as age increased. In particular, the decrease in lightness was remarkable in the region along the cheekbone, from the temple to the center of the cheek. Furthermore, we analyzed the seasonal changes of melanin distribution in the face area. This showed that the melanin index increased particularly in the cheekbone area in the summer when the influence of ultraviolet rays became large. Our novel methodology and the data presented in this article will be useful in various fields, such as dermatology, cosmetics, and computer vision.     

Effects of high‐pressure homogenisation on physicochemical characteristics of partially skimmed milk

The changes in partially skimmed milk (0.5% fat) physicochemical properties and proteins after high‐pressure homogenisation (HPH) at 100, 200 and 300 MPa were investigated. Processing parameters and changes in pH, ethanol precipitation stability, lightness, whey protein denaturation, hydrophobicity and viscosity were evaluated. No significant differences were found between milk pH and nonprotein nitrogen content before and after HPH. Ethanol stability, lightness and hydrophobicity increased when pressure was increased from 100 MPa to 300 MPa. Whey protein denaturation, evaluated through noncasein nitrogen, occurred only at 200 to 300 MPa, and viscosity increased just at 300 MPa. Therefore, HPH changed some milk physicochemical characteristics, mainly those related to protein content. These results highlight that HPH processing is a promising technology to improve partially skimmed milk mouth feel being suitable for dairy products manufacturing.     

流通领域中环境因素对盐渍榨菜品质变化的影响

研究盐渍榨菜在流通过程中环境因素:流通温度、流通湿度、光照强度、流通时间作用下的品质变化规律,采用响应面法得出各因素对盐渍榨菜品质影响,并确定相应的数学模型,从而得出影响因素与榨菜品质变化的关系.     

浅析火花塞点火间隙对发动机性能影响

火花塞间隙的大小,直接关系到两极间跳火的强弱。间隙过小会使火花变弱,也更容易使两点击发生跨连,不利于发动机工作,其间隙过大,不易使两级产生火花,所需点火能量就愈大。