Methods for evaluating volunteers’ contributions in a deforestation detection citizen science project

Today, due to the availability of free remote sensing data, efficient algorithms for image classification and increased connectivity and computing power, together with international policy initiatives, such as the United Nations Programme on Reducing Emissions from Deforestation and Forest Degradation (UN-REDD), more and more countries are investing in their own national forest monitoring schemes. However, tropical forests remain under threat worldwide. Recently, a citizen science project that enables citizens around the globe to be involved in forest monitoring tasks has been proposed, called “ForestWatchers” (www.forestwatchers.net). Its main goal is to allow volunteers (many of them with no scientific training) around the globe, with their own smartphones, tablets and notebooks, review satellite images of forested regions and confirm whether automatic assignments of forested and deforested regions are correct. Inspected images are then sent to a central database where the results are integrated to generate up-to-date deforestation maps. This approach offers a low-cost way to both strengthen the scientific infrastructure and engage members of the public in science. Here, we describe the methods developed within the scope of the ForestWatchers project to assess the volunteers’ performance. These tools have been evaluated with data of two of the project’s preliminary tasks. The first, called “BestTile”, asks volunteers to select which of several images of the same area has the least cloud cover, while in the second, called “Deforestation”, volunteers draw polygons on satellite images delimiting areas they believe have been deforested. The results from more than 500 volunteers show that using simple statistical tests, it is possible to achieve a triple goal: to increase the overall efficiency of the data collecting tasks by reducing the required number of volunteers per task, to identify malicious behavior and outliers, and to motivate volunteers to continue their contributions.     

Visualization of Thermo-Hydrodynamic Behavior in Flat-Plate Pulsating Heat Pipe with HFE-347

In this paper,the visualization of the thermo-hydrodynamic behavior in flat-plate pulsating heat pipe (FP-PHP) with HFE-347 is experimentally investigated.The F...     

一种改进的支持向量机模式分类方法

支持向量机(Support Vector Machine,SVM)是在统计学习理论基础上发展起来的一种新的机器学习方法,已成为目前研究的热点,并在模式识别领域有了广泛的应用.首先分析了支持向量机原理,随后引入一种改进的径向基核函数,在此基础上,提出了一种改进核函数的SVM模式分类方法.与基于IRIS数据,进行了计算机仿真实验,与基干模糊k-近邻的模式分类仿真结果比较,结果表明改进的SVM方法分类性能比模糊k-近邻算法(Fuzzy k-Nearest Neighbor,FKNN)的分类性能更好,运算时间更短,更易于实时实现.     

管状熔断器的典型失效模式和失效原因分析

管状熔断器是目前在电路设计中广泛采用的一种过流保护元件,分析了管状熔断器的熔断原理,总结了管状熔断器的典型失效模式和失效原因,给出管状熔断器的一般失效分析程序。     

Utility of RF MEMS miniature switched capacitors in phase shifting applications

This paper demonstrates research carried out towards the development of switched capacitors having miniature dimensions. Such devices are based on the Radio Frequency Micro Electro Mechanical Systems (RF MEMS) technique which has gained prominence in implementing a wide variety of microwave and millimetre devices till date. Switched capacitors having standard or conventional dimensions are prone to several limitations which are addressed by scaling down the standard dimensions by 150× times (in terms of area requirement). Such switched capacitors are employed to develop phase shifters working in K-band (22 GHz) frequency range to yield appreciable performance both in terms of electromechanical and RF characterizations. Such switched capacitors are utilized to develop phase shifters which find immense applications in the design of Phased Array RADARs. Switched capacitors fabricated on 500 µm thick quartz substrates, result in 30° phase shift (0.66 mm × 1 mm in dimension) with associated minimum −0.18 dB insertion loss and better than −21 dB reflection coefficient at 22 GHz frequency. Electromechanical characterization reports an actuation voltage of 14.6 V, mechanical vibration frequency of 2.5 MHz and a switching time of 620 ns respectively. Demonstrations showing complete realization of 180° phase shifter (4 mm × 1 mm) employing a cascaded arrangement of six similar 30° unit cells are also included in this paper.     

A New Fusion Method for Conflicting Evidence

A new conflicting evidence fusion method is proposed for the deficiency of Dempster's rule which can not fuse the conflicting evidence. Evidence is divided into three categories:believable evidence, non-conflicting evidence and conflicting evidence. The influences of these three categories of evidences on fusion results when discounted are analyzed respectively. On these bases, the evidence distance and the conjunctive conflict are utilized in sequence to recognize the believable evidence and non-conflicting evidence. The discounting factors of these two categories of evidences are set to one, which keeps the evidences support the true hypothesis to the greatest degree, and makes the fusion results focus onto the true hypothesis. Examples of some missile fault diagnosis show that the new method can effectively fuse the conflicting evidences, and is suited to fuse the relievable evidences. The new method improves the reliability and rationality of fusion results compared with traditional methods.     

Performance improvement of Si-CCD detector based backside reflected light and photon emission microscopy by FIB ultimate substrate thinning

In FA laboratories a significant number of photon emission microscopy (PEM) systems are equipped with the most common detector, namely cooled Si-CCD camera. Backside reflected light microscopy (RLM) and photon emission microscopy (PEM) using this detector are possible but strongly limited by the interaction of light with silicon substrate. In this work, we show the improvement of the RLM and PEM performed from the chip backside using standard cooled Si-CCD camera by localized focused-ion-beam (FIB) assisted silicon substrate removal. Thinning down the silicon substrate significantly improves signal-to-noise ratio of the techniques as well as their resolving properties. It also enables extended spectral analysis, also in the visible regime of the light spectrum. This study has been done using 120 nm technology process test structures.     

Broadband Eight-Way Differential SIW Power Divider with Bandpass-Filtering Response Using Novel Hybrid Multiple-via Probe and Multiple Radial Slots

A broadband eight-way differential substrate integrated waveguide (SIW) power divider with bandpass-filtering response by using novel hybrid multiple-via probe and multiple radial slots has been presented in this paper. The novel hybrid multiple-via probe are employed to achieve broadband impedance matching, while the multiple radial slots are used to improve the out-of-band rejection level. An eight-way differential SIW power divider with bandpass-filtering response is designed, fabricated, and measured. The measured results agree with the simulated ones closely in the desirable frequency range. The measured average insertion loss of the eight-way power divider is approximately 9.3 dB and input return loss is greater than 15 dB from 3.2 to 8.1 GHz. Moreover, the out-of-band rejection band with more than 25 dB attenuation from 9 GHz to more than 11 GHz is observed. A maximum amplitude imbalance of \(\pm 0.7\,\hbox { dB}\) is observed over the entire operating frequency range.     

中频数字载波跟踪环路分析与计算

文中针对二阶模拟、数字锁相环模型,推导了开环和闭环传递函数。对载波跟踪环鉴相器、清除滤波器和DDS增益等做了较为详尽的理论分析,得到了环路增益和带宽的数学推导结果。系统测试结果表明,此跟踪环路计算方法经测试证明是正确的、可靠的,分机满足实际载波跟踪和数字解调的动态特性要求。