Hydrogen sensor based on Pd-functionalized film bulk acoustic resonator

We present an application of the Pd-functionalized film bulk acoustic resonator for hydrogen detection. The resonator consisted of an AlN piezoelectric stack and a Bragg reflector has a working resonance near 2.23 GHz and a high performance. A 50 nm thick Pd film was coated on the top electrode as a specific layer to capture hydrogen. The absorption of hydrogen can trigger changes of elastic properties of the Pd layer, which affects the resonance frequency of the resonator. The experimental results show that the Pd-functionalized film bulk acoustic resonator can yield a rapid, sensitive, reversible and reproducible response to hydrogen in the concentrations from 0.3% to 2%. The advantages of this sensor, including the simple fabrication process, ease of detection method, rapid response and high sensitivity and working at room temperature, make this promising in the early alarm of hydrogen leaking.     

微机械气流式倾角传感器的研究

提出了一种能敏感倾角的微机械气流式传感器.采用微机械工艺在硅板上腐蚀出一个深槽,在深槽上设置2个有金属薄膜热敏电阻器的悬臂梁,用半圆球外壳封装成一个密闭腔体形成敏感元件;通过惠斯登电桥提取倾角电压信号;利用单片机和温度传感器构成补偿电路,实现温度补偿和线性度补偿.测试结果表明:测量范围为+30°,分辨率为优于0.1°,...     

冲击作用下碳纤维混凝土的力敏性试验研究

碳纤维混凝土(CFC)具有良好的力敏特性,能制成传感器用于混凝土结构的状态监测.利用钢球自由落体撞击圆柱形试样,进行了老化前后和不同撞击高度的试验,并分析了各因素对试样力敏性的影响.试验结果表明:试样的电阻变化对冲击作用响应快;老化前的试样在承载较小时,试样处于弹性区,电阻随压力增大而减小,承载较大时,试样进入弹塑性区,电阻随压力增大而增大;老化后的试样,承载即进入弹塑性区.     

一种基于android轻型网关敏感数据泄露检测模型

针对智慧家居控制系统中基于android系统轻型网关的敏感数据泄露问题,提出了一种基于android本地库层污点传播和应用层控制的分层互连检测模型。通过在IPC Binder通信时标记污点,在待测应用进程调用本地网络套接字函数时检测污点,分析污点传播路径并计算泄露指数,实现对敏感数据泄露的跟踪检测。实验表明该模型能够检测出各个敏感数据源以明文或密文方式的数据泄露,准确率达到93%以上,同时性能开销不超过1%,从而实现对Android轻型网关敏感数据泄露的有效检测,实用性强,并为之后相关研究提供了新方向。     

Sensitive-by-distance: quasi-health data in the algorithmic era

This article offers a new perspective on the boundaries between health and non-health data in the age of ‘Quantified-Self’ apps: the ‘data-sensitiveness-by-computational-distance’ approach-or, more simply, the ‘sensitive-by-distance’ approach. This approach takes into account two variables: the intrinsic sensitiveness (a static variable) of personal data and the computational distance (a dynamic variable) between some kinds of personal data and pure health (or sensitive) data, which depends upon computational capacity. From an objective perspective, computational capacity depends on the level of development of data retrieval technologies at a certain moment, the availability of ‘accessory data’, and the applicable legal restraints on processing data. From a subjective perspective, computational capacity depends on the specific data mining efforts (or the ability to invest in them) taken by a given data controller: economic resources, human resources, and the use of accessory data. A direct consequence of the expansion of augmented humanity in collecting and inferring personal data is the increasing loss of health data processing ‘legibility’ for data subjects. In order to address this issue, we propose exploiting the existing legal tools in the General Data Protection Regulation to empower data subjects (the right to data access, the right to know the logic involved in automated decision-making, data portability, etc.).     

云环境下基于秘密共享的海洋遥感影像认证方案

云存储模式的出现为海量海洋遥感影像的存储和管理带来了机遇,越来越多的用户选择将海洋遥感影像数据移植到云中,但云存储环境的开放性对海洋遥感影像数据的安全性提出了挑战。以保障云环境下海洋遥感敏感数据的安全性为前提,提出一种影像认证方案,将哈希函数与(k,n)门限秘密共享方法相结合,检测敏感区影像信息变化,并对加密前和恢复后的影像进行一致性验证,保护加密影像数据的机密性。同时,为避免n个子秘密中,因多于n-k个子秘密的篡改或丢失,造成敏感区影像不可恢复情况的发生,采用对敏感区影像进行分块的策略,对每个子影像块做进一步的秘密共享处理,以保证部分影像的无损恢复。实验对比分析表明,所提出的安全认证方案可以有效防止秘密恢复过程中的欺诈行为,同时可获得比传统方法更高的遥感影像云存储安全性。     

An eigenvalue approach to the risk sensitive control problem in near monotone case

Risk sensitive control problem under near monotonicity condition is considered. We prove existence of a solution to the corresponding Hamilton-Jacobi-Bellman equation by an eigenvalue approach. Existence of an optimal control has also been proved.     

基于信息熵与动态区域分割的半脆弱数字水印算法

已有的半脆弱水印算法大多数采取了双步长的固定量化方法,对载体图像没有针对攻击特性给予考虑,只将载体图像分为平滑和纹理两个区域,使得水印的鲁棒性进入了一个瓶颈状态。为了进一步提高水印的鲁棒性,提出了一种基于图像动态分割技术和信息熵的半脆弱水印算法。图像动态分割技术将图像分为若干个嵌入区域,并且确定各个嵌入区域的嵌入强度;基于信息熵的步长量化算法将信息熵引入到步长量化的计算方法中,能够有效衡量不同嵌入区域所携带的敏感信息量。实验结果表明,提出的算法与已有半脆弱水印算法相比,视觉掩蔽性好,鲁棒性也有了较明显的提高。     

Co-Mg-NiO系氧敏材料的研究

研究了Co -Mg -NiO系氧敏材料在氧分压为 1～ 10 -2 3 atm(1atm =10 1.32 5kPa) ,温度为 70 0～10 0 0℃范围内的电导率与氧分压及温度的关系 ,讨论了材料的氧敏特性、导电机理 ,得出高温下材料中的缺陷类型随氧分压的降低主要是单电离和双电离的金属缺位 ,并得到了材料的某些参数。     

Learning to hash: forgiving hash functions and applications

The problem of efficiently finding similar items in a large corpus of high-dimensional data points arises in many real-world tasks, such as music, image, and video retrieval. Beyond the scaling difficulties that arise with lookups in large data sets, the complexity in these domains is exacerbated by an imprecise definition of similarity. In this paper, we describe a method to learn a similarity function from only weakly labeled positive examples. Once learned, this similarity function is used as the basis of a hash function to severely constrain the number of points considered for each lookup. Tested on a large real-world audio dataset, only a tiny fraction of the points (~0.27%) are ever considered for each lookup. To increase efficiency, no comparisons in the original high-dimensional space of points are required. The performance far surpasses, in terms of both efficiency and accuracy, a state-of-the-art Locality-Sensitive-Hashing-based (LSH) technique for the same problem and data set.