Improving Touschek lifetime and synchrotron frequency spread by passive harmonic cavity in the storage ring of SSRF

Beam lifetime of a synchrotron is dominated by Touschek scattering.In the beamline Phase Ⅱ project of Shanghai synchrotron radiation facility,a passive third harmonic cavity is to be installed for bunch lengthening and instability suppressing.In this paper,the beam dynamics of the cavity is investigated.The parameters of passive operation are optimized to cancel the slope of RF voltage and lengthen the bunches.The Touschek lifetime increases are estimated for optimum and non-optimum voltage flattening.A tolerance of the operation is studied in case that there is a shift on detuning angle.The effect caused by reduction in harmonic voltage generated by lengthened bunch distribution is also estimated using iteration method.An increase in synchrotron frequency spread due to nonlinearity of the voltage giving to the bunch is found by using tracking simulation.This spread can help in damping coupled bunch instability through Landau damping.     

Vibration signal analysis for condition monitoring of puffer‐type high‐voltage circuit breakers using wavelet transform

Nowadays, the goals of electrical supply utilities are to reduce equipment failures, extend service life, increase equipment reliability, and reduce their related operating and maintenance costs. The high‐voltage circuit breaker is an important element in the electrical network. In order to determine or to detect abnormal conditions inside a circuit breaker, powerful vibration analytical techniques have been proposed. In this paper, a vibrational analysis is carried out by analyzing the signal in the time–frequency domain under no‐load switching operations with a commercially available high‐voltage puffer‐type circuit breaker without opening its major parts. Vibration of the circuit breaker poles, operating mechanism, and various monitored parameters were recorded under normal and variable operating conditions. Moreover, a synthetic mechanical damage introduced deliberately is also investigated. The experimental result indicates that mechanical defects can be detected by analyzing the vibration signal. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Structure of the olfactory receptor organs,their GABAergic neural pathways,and modulation of mating behavior,in the giant freshwater prawn,Macrobrachium rosenbergii

In the giant male prawn, Macrobrachium rosenbergii, the olfactory system is thought to be the main pathway for modulating sexual behavior through pheromone perception. In this report, we first used gross anatomical, histological, and SEM methods to describe the structures of the olfactory receptors (sensilla setae), their neural pathways, and possible role in modulating mating behavior. On the surfaces of antennule and antenna filaments there are four types of sensory receptors, viz single spike‐like setae, single flagellum‐like setae, multiple flagella‐like setae, and aesthetascs (ASs). The ASs, which had previously been proposed to be odor receptor setae, are found only on the short filament of lateral antennule (slAn). Each AS on the slAn connects with olfactory receptor neurons (ORNs), whose axons form an outer central antennule nerve (ocAnNv), which then connects with the olfactory neutrophil (ON) of the brain. Thus, the slAn is the major olfactory organ that conveys sensory inputs from each AS to the ON within the deutocerebrum. GABA immunoreactivity was present in ASs, neurons of ORNs, inner central antennular, lateral tegumentary nerve, ocAnNv and the ON, inferring that GABA is the likely neurotransmitter in modulating olfaction. Disruption of the slAn by ablation or covering with Vaseline, resulted in significant reduction of mating behavior, indicating that this organ is crucial for sex pheromone perception. Identification of the active pheromones and further bioassays are now being performed. Microsc. Res. Tech. 76:572–587, 2013. © 2013 Wiley Periodicals, Inc.     

Empirical Circuit Breaker Failure Rate Assessment and Modeling in a Preventive Maintenance Application

This article presents an analysis of the failure rates of SF6 puffer circuit breakers in the 230-kV voltage class. Historical failure recorded data for existing power circuit breakers in high-voltage substations in Thailand from 1992 to 2011 were retrieved. Subsequently, the data were analyzed and classified based on the causes of failure related to circuit breaker sub-components. The failure rates of the individual circuit breaker sub-components were determined. These failure rates were then categorized into three main circuit breaker component categories based on their functionality, which includes the live part and insulation, operating mechanism, and control part. The failure rates of the individual circuit breaker sub-components were calculated, and their associated probability distributions were estimated using Weibull distribution functions. The resulting Weibull distribution parameters were subsequently utilized in a circuit breaker preventive maintenance application to aid in the decision-making process for setting the maintenance schedule of the circuit breaker components. Finally, circuit breaker reliability is also monitored. This proposed method can also be applied to other high-voltage equipment in power systems.     

Neuronal classification and distribution in the central nervous system of the female mud crab,Scylla olivacea

The mud crab, Scylla olivacea, is one of the most economically valuable marine species in Southeast Asian countries. However, commercial cultivation is disadvantaged by reduced reproductive capacity in captivity. Therefore, an understanding of the general and detailed anatomy of central nervous system (CNS) is required before investigating the distribution and functions of neurotransmitters, neurohormones, and other biomolecules, involved with reproduction. We found that the anatomical structure of the brain is similar to other crabs. However, the ventral nerve cord (VNC) is unlike other caridian and dendrobrachiate decapods, as the subesophageal (SEG), thoracic and abdominal ganglia are fused, due to the reduction of abdominal segments and the tail. Neurons in clusters within the CNS varied in sizes, and we found that there were five distinct size classes (i.e., very small globuli, small, medium, large, and giant). Clusters in the brain and SEG contained mainly very small globuli and small‐sized neurons, whereas, the VNC contained small‐, medium‐, large‐, and giant‐sized neurons. We postulate that the different sized neurons are involved in different functions. Microsc. Res. Tech. 77:189–200, 2014. © 2013 Wiley Periodicals, Inc.     

Risk assessment based on condition and importance criteria for power transformer in Thailand transmission network

This paper proposes an innovative risk‐assessment strategy based on condition and importance criteria for power transformer maintenance in a transmission network. The condition assessment is performed by the analysis of different diagnosis methods such as electrical test, insulating oil test, and visual inspection. The importance assessment is evaluated from various aspects such as load criticality, impact on system stability, possibility of failure, failure consequence, damage to property, as well as social impact and environmental concerns. Weighting and scoring techniques are applied to determine the actual condition and importance of the power transformer with regard to condition and importance aspects. By combining the condition and importance assessment, the overall risk to the power transformer is assessed and differentiated into nine categories in the risk matrix from the lowest to the highest risk. Additionally, by applying distance ‘d’ technique, the risk‐based assessment matrix for the power transformer can be identified into five zones: healthy, good, moderate, bad, and risky. These five zones are also represented by color indicators as green, blue, yellow, orange, and red, which are further interpreted to five steps of maintenance tasks. The transformer with longer distance ‘d’ is subjected to higher risk and should be maintained first. By this method, a total of 19 power transformers were analyzed and are presented as examples for risk‐based maintenance. Then, risks of a total 598 power transformers are shown in the risk matrix. A computerized web application program is developed for practical implementation in a utility in Thailand. Finally, the systematic risk assessment and maintenance task of the power transformer fleet in Thailand are effectively managed. Thereby, the total maintenance cost of power transformer can be reduced. © 2014 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.