高压输电线路驱鸟试验研究

根据齐齐哈尔地区高压输电线路鸟害事故频繁发生的情况,分析了鸟害产生的原因,对苍鹭、白鹳等大型鸟类制定并进行了驱赶试验,即光照驱鸟、超声波驱鸟、声音驱鸟、短针微创式防鸟刺驱鸟、电击板驱鸟实验.分析了各种驱鸟方式的优势和不足,并结合实际应用环境,选择最有效的驱鸟方式进行驱鸟,降低高压输电线路鸟害故障率,保障了电网的安全运行...     

Fast recognition of bird sounds using extreme learning machines

Recognition of bird species by their sounds can bring considerable significance to both ecologists and ornithologists for measuring the biodiversity in the reserves, and studying climate changes. In this letter, we propose an efficient method based on an extreme learning machine (ELM) to classify bird sounds of 86 species of birds in very limited training and testing time. Experimental results prove that, the proposed ELM method can achieve the best recognition performance (81.1 %, unweighted average recall) compared with K‐nearest neighbours (K‐NN), support vector machines (SVM), neural networks (NN), and deep neural networks (DNN) pre‐trained by an autoencoder. In addition, ELM requires the least total time for training and testing (2.047 ± 0.034 s). © 2016 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

美国输电线路和变电站电气设备防鸟害措施

阐述输电线路和变电站电力设备防鸟害是一个世界性的课题;如何找到较好的与鸟和谐共处的办法,把鸟无论是飞行碰撞还是栖息筑巢对电力系统的影响减少到最低限度,是国内外共同关注的问题。介绍美国输电线路和变电站电力设备防鸟害的各项方法和措施,对防撞击、防触电以及缓冲技术进行分析,对变电站的防鸟害措施进行探讨,以期为国内输电线路和变电站电力设备防鸟害提供借鉴。     

Failures in outdoor insulation caused by bird excrement

The bird excrement, combined with humidity, causes line outages in transmission lines. In order to standardize the criteria to solve the problem, a research project was developed in México. The solutions found in worldwide review can be classified into four groups: elimination of birds, devices of dissuasion, physical barriers, and covering devices. The first group includes all bird elimination techniques. These alternatives are forbidden in México, and in most of the countries. The second group has shown to be effective at the beginning of its application; however once the birds are habituated to the device, it loses its effectiveness. The efficiency of the third group, the use of physical barriers, is high, as demonstrated by more than a few review reports informing drastic reductions of flashovers on the transmission lines where they have been installed. The fourth group is conformed by components whose function is to protect or to cover the insulation. According to the experience in Mexico, covering devices have shown to be very effective. The contamination by bird excrement has not a unique solution. The most viable solution is a combination of alternatives. Even though, a solution adopted for a region may not be suitable for another region. Therefore, each case should be approached according to the particular conditions of the region.     

Artefacts in magnetic resonance imaging caused by dental material

A common problem in computer tomography (CT) based imaging of the oral cavity is artefacts caused by dental restorations. The aim of this study was to investigate whether magnetic resonance imaging (MRI) of the oral cavity would be less affected than CT by artefacts caused by typical dental restorative alloys. In order to assess the extent of artefact generation, corresponding MRI scans of the same anatomic region with and without dental metal restorations were matched using a stereotactic frame. MRI imaging of the oral and maxillofacial region could be performed without reduction of the image quality by metallic dental restorations made from titanium, gold or amalgam. Dental restorations made from titanium, gold or amalgam did not reduce the image quality of the MRI sequence used in imaging of the oral and maxillofacial region for dental implant planning. In this respect MRI is superior to CT in implant planning.     

In-vivo human brain molecular imaging with a brain-dedicated PET/MRI system

Advances in the new-generation of ultra-high-resolution, brain-dedicated positron emission tomography-magnetic resonance imaging (PET/MRI) systems have begun to provide many interesting insights into the molecular dynamics of the brain. First, the finely delineated structural information from ultra-high-field MRI can help us to identify accurate landmark structures, thereby making it easier to locate PET activation sites that are anatomically well-correlated with metabolic or ligand-specific organs in the neural structures in the brain. This synergistic potential of PET/MRI imaging is discussed in terms of neuroscience and neurological research from both translational and basic research perspectives. Experimental results from the hippocampus, thalamus, and brainstem obtained with ¹⁸F-fluorodeoxyglucose and ¹¹C-3-amino-4-(2-dimethylaminomethylphenylsulfanyl)benzonitrile are used to demonstrate the potential of this new brain PET/MRI system.     

The strengths of in vivo magnetic resonance imaging (MRI) to study environmental adaptational physiology in fish

Adaptational physiology studies how animals cope with their environment, even if this environment is subject to permanent fluctuations such as tidal or seasonal variations. Aquatic organisms are generally more prone to be exposed to osmotic, hypoxic and temperature challenges than terrestrial animals. Some of these challenges are more restraining in an aquatic environment. To date, very few studies have used in vivo magnetic resonance imaging (MRI) to uncover the physiological mechanisms that respond to or compensate for these challenges. This paper provides an overview of what has been accomplished thus far by using MRI to study the environmental physiology of fish. It introduces the reader to the use of small teleost fish such as carp (12 cm, 60 g) and eelpout (25 cm, 50 g) as models for such research and to provide new perceptions into the applicability of MRI tools based on new insights into the nature of MRI contrast. Representative MRI studies have made contributions to the identification of the lack of cell volume repair in stenohaline fish during osmotic stress. They have studied the underlying physiological mechanisms of brain anoxia tolerance in fish and have qualified the role of the cardio-circulatory system in setting thermal tolerance windows of fish.     

复合I型绝缘子的直流鸟粪闪络特性研究

为减少鸟害事故发生,提高线路运行可靠性,有必要对鸟粪闪络特性进行研究。本实验采用了浸渍有鸟粪模拟液的棉布条来模拟鸟粪,以复合I型绝缘子为研究对象,试验模拟研究了在直流电压下,鸟粪从均压环正上方和侧上方下落时,其空间位置对起晕电压、击穿电压和击穿场强的影响。研究表明,当模拟鸟粪与均压环距离增大时,击穿电压升高,击穿场强会随着间隙距离的增大而逐渐降低,接近于棒－棒间隙的击穿电场强度。最后,利用COMSOL有限元仿真软件进行了计算。试验和仿真结果对输电线路的建设和维护有一定的参考价值。     

500kV侯临线(临汾段)鸟害防治分析

通过对临汾鸟类活动状况与外地500kV线路鸟害故障分析，认识到500kV侯临线(临汾段)鸟害故障的可能性，并提出防范重点和防治对策。     

输电线路防鸟网在信阳供电公司的研制与应用

介绍了输电线路防鸟网的作用,利用丝网封堵住鸟类筑巢的位置及飞行途径,使鸟类在杆塔上无法停留筑巢.线路防鸟网起到了防乌、护鸟的作用,减小了鸟类搭窝对输电线路造成的危害.     

Ex-vivo cellular MRI with b-SSFP: quantitative benefits of 3 T over 1.5 T

INTRODUCTION: The use of MRI with iron-based magnetic nanoparticles for imaging cells is a rapidly growing field of research. We have recently reported that single iron-labeled cells could be detected, as signal voids, in vivo in mouse brains using a balanced steady-state free precession imaging sequence (b-SSFP) and a customized microimaging system at 1.5 T. METHODS: In the current study we assess the benefits, and challenges, of using a higher magnetic field strength for imaging iron-labeled cells with b-SSFP, using ex vivo mouse brain specimens imaged with near identical systems at 1.5 and 3.0 T. RESULTS: The substantial banding artifact that appears in 3 T b-SSFP images was readily minimized with RF phase cycling, allowing for banding-free b-SSFP images to be compared between the two field strengths. This study revealed that with an optimal 3 T b-SSFP imaging protocol, more than twice as many signal voids were detected as with 1.5 T. CONCLUSION: There are several factors that contributed to this important result. First, a greater-than-linear SNR gain was achieved in mouse brain images at 3 T. Second, a reduction in the bandwidth, and the associated increase in repetition time and SNR, produced a dramatic increase in the contrast generated by iron-labeled cells.     

架空输电线路新型防鸟装置的研制及应用

鸟害故障在宁夏石嘴山地区110 kV及以上输电线路故障中所占比例逐年升高,已成为影响电网安全稳定运行的主要因素之一,亟需加强治理,因此,对红外线感应超声波脉冲驱鸟器和磁吸式防鸟挡板两种防鸟装置进行研制,对他们的结构、工作机制、安装应用方式进行设计。研制出的成品装置在鸟害高发的某110 kV输电线路进行试验应用。试验结果表明,红外感应超声波脉冲驱鸟器能准确感知鸟类大小、飞行速度等关键信息,并在适当位置发射脉冲波。磁吸式防鸟挡板安装简便,防护范围满足要求。两者组合应用可有效防范鸟害故障。     

A systematic review on the use of quantitative imaging to detect cancer therapy adverse effects in normal-appearing brain tissue

Cancer therapy for both central nervous system (CNS) and non-CNS tumors has been previously associated with transient and long-term cognitive deterioration, commonly referred to as ‘chemo fog’. This therapy-related damage to otherwise normal-appearing brain tissue is reported using post-mortem neuropathological analysis. Although the literature on monitoring therapy effects on structural magnetic resonance imaging (MRI) is well established, such macroscopic structural changes appear relatively late and irreversible. Early quantitative MRI biomarkers of therapy-induced damage would potentially permit taking these treatment side effects into account, paving the way towards a more personalized treatment planning.

This systematic review (PROSPERO number 224196) provides an overview of quantitative tomographic imaging methods, potentially identifying the adverse side effects of cancer therapy in normal-appearing brain tissue. Seventy studies were obtained from the MEDLINE and Web of Science databases. Studies reporting changes in normal-appearing brain tissue using MRI, PET, or SPECT quantitative biomarkers, related to radio-, chemo-, immuno-, or hormone therapy for any kind of solid, cystic, or liquid tumor were included. The main findings of the reviewed studies were summarized, providing also the risk of bias of each study assessed using a modified QUADAS-2 tool. For each imaging method, this review provides the methodological background, and the benefits and shortcomings of each method from the imaging perspective. Finally, a set of recommendations is proposed to support future research.

     

Absolute cerebral blood flow measured by dynamic susceptibility contrast MRI: a direct comparison with Xe-133 SPECT

Absolute regional cerebral blood flow (CBF) was measured in ten healthy volunteers, using both dynamic susceptibility-contrast (DSC) magnetic resonance imaging (MRI) and Xe-133 SPECT within 4 h. After i.v. injection of Gd-DTPA-BMA (0.3 mmol/kg b.w.), the bolus was monitored with a Simultaneous Dual FLASH pulse sequence (1.5 s/image), providing one slice through brain tissue and a second slice through the carotid artery. Concentration C(t) is proportional to -(1/TE) ln[S(t)/S(0)] was related to CBF as C(t) = CBF [AIF(t) x R(t)], where AIF is the arterial input function and R(t) is the residue function. A singular-value-decomposition-based deconvolution technique was used for retrieval of R(t). Absolute CBF was given by Zierler's area-to-height relation and the central volume principle. For elimination of large vessels (ELV), all MRI-based CBF values exceeding 2.5 times the mean CBF value of the slice were excluded. A correction for partial-volume effects (CPVE) in the artery used for AIF monitoring was based on registration of signal in a phantom with tubes of various diameters (1.5-6.5 mm), providing an individual concentration correction factor applied to AIF data registered in vivo. In the Xe-133 SPECT investigation, 3,000-4,000 MBq of Xe-133 was administered intravenously, and CBF was calculated using the Kanno Lassen algorithm. When ELV and CPVE were applied, DSC-MRI showed average CBF values from the entire slice of 43 +/- 10 ml/(min 100 g) (small-artery AIF) and 48 +/- 17 ml/(min 100 g) (carotid-artery AIF) (mean +/- S.D., n = 10). The corresponding Xe-133-SPECT-based CBF was 33 +/- 6 ml/(min 100 g) (n = 10). The relationships of CBF(MRI) versus CBF(SPECT) showed good linear correlation (r = 0.74-0.83).     

Human rapid acquisition with relaxation enhancement imaging at 8 T without specific absorption rate violation

A standard fast imaging sequence, rapid acquisition with relaxation enhancement (RARE), has been applied to human magnetic resonance at 8 T. RARE is known for its speed, good contrast and high RF power content. HighlyT ₂ weighted images, the hallmark of RARE imaging, were acquired from the human brain. It is demonstrated that whileT ₂ values may be reduced at 8 T, high quality RARE images could still be acquired at this field strength. Most importantly however, it is demonstrated that RARE images could be acquired without violating specific absorption rate (SAR) guidelines. Since it is well known thatT ₂ weighted images are of significant value in clinical diagnosis, the implementation of RARE at this field strength will provide ultra high field MRI (UHFMRI) with a valuable imaging protocol at this field strength without exceeding SAR limitations.     

Segmentation of human brain using structural MRI

Segmentation of human brain using structural MRI is a key step of processing in imaging neuroscience. The methods have undergone a rapid development in the past two decades and are now widely available. This non-technical review aims at providing an overview and basic understanding of the most common software. Starting with the basis of structural MRI contrast in brain and imaging protocols, the concepts of voxel-based and surface-based segmentation are discussed. Special emphasis is given to the typical contrast features and morphological constraints of cortical and sub-cortical grey matter. In addition to the use for voxel-based morphometry, basic applications in quantitative MRI, cortical thickness estimations, and atrophy measurements as well as assignment of cortical regions and deep brain nuclei are briefly discussed. Finally, some fields for clinical applications are given.     

用钢绞线制作防鸟网防范输电线路上大鸟(黑鹳)造成鸟粪闪烙的实践

输电线路绝缘子受到鸟粪污染会发生闪烙掉闸,简称鸟害,为了防止线路不受鸟害,传统是采取加鸟刺的方法,但这种方法有很大的负作用,为此论述了一种用钢绞线制作防鸟网防范输电线路上大鸟(黑鹳)造成鸟粪闪烙的方法,它克服了加鸟刺的负作用,并在实践中取得了明显的防鸟效果。     

Near real-rime MRI of interstitial laser photocoagulation ofin vivo rat liver

Magnetic resonance imaging (MRI) is showing considerable promise as a monitor for interventional procedures. Laser surgery is MRI compatible, and temperature-sensitive imaging techniques can be usefully applied to these procedures. We have been investigatingT ₁derived temperature-dependent imaging as a monitor for interstitial laser photocoagulation (ILP) in rat liver.In vitro experiments suggested that temperature calibration may be achieved. We have investigated ILPin vivo using short TR spin-echo imaging sequences taking one set of images every 30 s during and after the procedure. Our resultsin vivo suggest that this simple model may be inadequate for temperature mapping as the biological reaction to the ILP is on a similar time scale to that of the procedure. Nonetheless, MRI shows well-defined, repeatable signal changes that can be related to histological borders.     

智能识别和主动驱赶的防鸟害装置研究

研制了一种基于智能识别和主动驱赶的超声波智能驱鸟器,用于防止输电线路遭受乌害影响。驱鸟装置系统主要由探测模块、电源模块、控制模块和执行模块组成。该装置使用先进的多普勒雷达侦测技术和声音方向传感技术对鸟类进行侦测,有效防护区域大,当鸟类进入危险区域时进行有效驱赶。而且装置具有智能学习能力,能有效地驱赶鸟类,并防止鸟类的适应能力。     

架空输电线路绿色防鸟害模式探讨

为实现在人与自然、电网与鸟类和谐共处的前提下降低架空输电线路的鸟害跳闸率,通过分析架空输电线路鸟害故障的成因、类型和特性,并总结深圳电网多年来的防鸟害工作经验,提出驱引结合的绿色防鸟害理念及其具体的防范措施.“驱”即采用驱鸟装置驱赶鸟类;“引”即在输电杆塔上安装人工鸟笼吸引鸟类在笼中筑巢,避免鸟类在杆塔上乱搭乱建.深圳...