PerfMon: Measuring Application-Level Performance in a Large-Scale Campus Wireless Network

WiFi has become one of the most popular ways to access the Internet.However,in large-scale campus wireless networks,it is challenging for network administrators to provide optimized access quality without knowledge on fine-grained traffic characteristics and real network performance.In this paper,we implement PerfMon,a network performance measurement and diagnosis system,which integrates collected multi-source datasets and analysis methods.Based on PerfMon,we first conduct a comprehensive measurement on application-level traffic patterns and behaviors from multiple dimensions in the wireless network of T university(TWLAN),which is one of the largest campus wireless networks.Then we systematically study the application-level network performance.We observe that the application-level traffic behaviors and performance vary greatly across different locations and device types.The performance is far from satisfactory in some cases.To diagnose these problems,we distinguish locations and device types,and further locate the most crucial factors that affect the performance.The results of case studies show that the influential factors can effectively characterize performance changes and explain for performance degradation.

Brief Talk About Big Data Graph Analysis and Visualization

Graphical methods are used for construction.Data analysis and visualization are an important area of applications of big data.At the same time,visual analysis is also an important method for big data analysis.Data visualization refers to data that is presented in a visual form,such as a chart or map,to help people understand the meaning of the data.Data visualization helps people extract meaning from data quickly and easily.Visualization can be used to fully demonstrate the patterns,trends,and dependencies of your data,which can be found in other displays.Big data visualization analysis combines the advantages of computers,which can be static or interactive,interactive analysis methods and interactive technologies,which can directly help people and effectively understand the information behind big data.It is indispensable in the era of big data visualization,and it can be very intuitive if used properly.Graphical analysis also found that valuable information becomes a powerful tool in complex data relationships,and it represents a significant business opportunity.With the rise of big data,important technologies suitable for dealing with complex relationships have emerged.Graphics come in a variety of shapes and sizes for a variety of business problems.Graphic analysis is first in the visualization.The step is to get the right data and answer the goal.In short,to choose the right method,you must understand each relative strengths and weaknesses and understand the data.Key steps to get data:target;collect;clean;connect.

Detecting conflict of heterogeneous access control policies

Policy conflicts may cause substantial economic losses.Although a large amount of effort has been spent on detecting intra-domain policy conflict,it can not detect conflicts of heterogeneous policies.In this paper,considering background knowledge,we propose a conflict detection mechanism to search and locate conflicts of heterogeneous policies.First,we propose a general access control model to describe authorization mechanisms of cloud service and a translation scheme designed to translate a cloud service policy to an Extensible Access Control Markup Language(XACML)policy.Then the scheme based on Multi-terminal Multi-data-type Interval Decision Diagram(MTMIDD)and Extended MTMIDD(X-MTMIDD)is designed to represent XACML policy and search the conflict among heterogeneous policies.To reduce the rate of false positives,the description logic is used to represent XACML policy and eliminate false conflicts.Experimental results show the efficiency of our scheme.

Development and Application of Time-Resolved Surface Plasmon Resonance Spectrometer

Surface plasmon resonance (SPR) sensor, an optical sensor exploiting special electromagnetic waves-surface plasmon polaritons to probe interactions between an analyte in solution and a molecular recognition element immobilized on the SPR sensor surface, has been widely used in various realms, such as investigating biomolecular interactions and binding properties, detection of biological and chemical analytes, environmental monitoring, food safety and medical diagnostics. This paper reviews the development of SPR sensors and SPR commercial instruments, and emphatically introduces the time-resolved surface plasmon resonance (TR-SPR) techniques. The excellent performances of high sensitivity and rapid detection are easily achieved with TR-SPR spectrometer, whereas the traditional SPR spectrometer cannot be accomplished. Therefore, TR-SPR spectrometer is appropriate for real time analysis of bio-recognition events and small molecular dynamics. However, only two commercial TR-SPR instruments have been exhibited at present, Thermo FT-SPR 100 and Autolab ESPRIT (SPRINGLE). Unfortunately, the high-priced instruments are not suitable for extensive applications in laboratories at present. Herein, a novel commercial TR-SPR spectrometer has been introduced in this review.

Privacy Computing: Concept, Computing Framework, and Future Development Trends

With the rapid development of information technology and the continuous evolution of personalized ser- vices, huge amounts of data are accumulated by large internet companies in the process of serving users. Moreover, dynamic data interactions increase the intentional/unintentional persistence of private infor- mation in different information systems. However, problems such as the cask principle of preserving pri- vate information among different information systems and the dif culty of tracing the source of privacy violations are becoming increasingly serious. Therefore, existing privacy-preserving schemes cannot pro- vide systematic privacy preservation. In this paper, we examine the links of the information life-cycle, such as information collection, storage, processing, distribution, and destruction. We then propose a the- ory of privacy computing and a key technology system that includes a privacy computing framework, a formal de nition of privacy computing, four principles that should be followed in privacy computing, ffect algorithm design criteria, evaluation of the privacy-preserving effect, and a privacy computing language. Finally, we employ four application scenarios to describe the universal application of privacy computing, and discuss the prospect of future research trends. This work is expected to guide theoretical research on user privacy preservation within open environments.

Optoelectronic and photocatalytic properties of I–III–VI QDs: Bridging between traditional and emerging new QDs

Due to the quantum size effect and other unique photoelectric properties,quantum dots(QDs)have attracted tremendous interest in nanoscience,leading a lot of milestone works.Meantime,the scope and scientific connotation of QDs are constantly expanding,which demonstrated amazing development vitality.Besides the well-developed Cd-containing Ⅱ-Ⅵ semiconductors,QDs of environmentally friendly Ⅰ-Ⅲ-Ⅵ(Ⅰ=Cu,Ag;Ⅲ=Ga,In;Ⅵ=S,Se)chalcogenides have been a hot spot in the QDs family,which are different from traditional Ⅱ-Ⅵ QDs in terms of multi-composition,complex defect structure,synthetic chemistry and optical properties,bringing a series of new laws,new phenomena and new challenges.The composition of Ⅰ-Ⅲ-Ⅵ chalcogenides and their solid solutions can be adjusted within a very large range while the anion framework remains stable,giving them excellent capability of photoelectric property manipulation.The important features of Ⅰ-Ⅲ-Ⅵ QDs include wide-range bandgap tuning,large Stokes shift and long photoluminescence(PL)lifetime,which are crucial for biological,optoelectronic and energy applications.This is due to the coexistence of two or more metal cations leading to a large number of intrinsic defects within the crystal lattice also known as deep-donor-acceptor states,besides the commonly observed surface defects in all QDs.However,a profound understanding of their structure and optoelectronic properties remains a huge challenge with many key issues unclear.On one hand,the achievements and experience of traditional QD research are expected to provide vital value for further development of Ⅰ-Ⅲ-Ⅵ QDs.On the other hand,the understanding of the emerging new QDs,such as carbon and other 2D materials,are even more challenging because of the dramatically different composition and structure from Ⅱ-Ⅵ semiconductors.For this,Ⅰ-Ⅲ-Ⅵ QDs,as a close relative to Ⅱ-Ⅵ QDs but with much more complex composition and structure variation,provide a great opportunity as a gradual bridge to make up the big gap between traditional QDs and emerging new QDs,such as carbon dots.Here,we hope to compare the research progress of Ⅰ-Ⅲ-Ⅵ QDs and Ⅱ-Ⅵ QDs,in an effort to comprehensively understand their structure,synthetic chemistry,optical electronic and photocatalytic properties.We further give insights on the key potential issues of Ⅰ-Ⅲ-Ⅵ QDs from the perspective of bridging between traditional QDs and emerging carbon dots,especially the profound principles behind synthetic chemistry,PL mechanism and optoelectronic applications.

Expanding Hot Code Path for Data Cleaning on Software Graph

Graph analysis can be done at scale by using Spark GraphX which loading data into memory and running graph analysis in parallel.In this way,we should take data out of graph databases and put it into memory.Considering the limitation of memory size,the premise of accelerating graph analytical process reduces the graph data to a suitable size without too much loss of similarity to the original graph.This paper presents our method of data cleaning on the software graph.We use SEQUITUR data compression algorithm to find out hot code path and store it as a whole paths directed acyclic graph.Hot code path is inherent regularity of a program.About 10 to 200 hot code path account for 40%-99%of a program’s execution cost.These hot paths are acyclic contribute more than 0.1%-1.0%of some execution metric.We expand hot code path to a suitable size which is good for runtime and keeps similarity to the original graph.

Gap engineering of sandwich plasmonic gap nanostructures for boosting plasmon-enhanced electrocatalysis

Plasmonic catalysis is emerging as a dynamic field in heterogeneous catalysis and holds great promise for the efficient utilization of solar energy.Central to the development of plasmonic catalysis is the design of efficient plasmonic nanocatalysts.In this report,plasmonic gap nanostructures(PGNs)on the basis of Au@poly(o-phenylenediamine)(POPD)@Pd sandwich nanostructures are synthesized as plasmonic nanocatalysts by an in-situ reduction synthetic strategy,which allows for the precise engineering of the POPD gap size between plasmonic Au and catalytic Pd components.The introduction of conducting POPD nanogap in PGNs not only effectively enhances their light harvesting capability,but also provides an effective charge transfer channel for harnessing the photogenerated hot charge carriers.In this respect,distinct gap-dependent performances in plasmon-enhanced electrocatalysis of ethanol oxidation reactions(EOR)are demonstrated with the PGN nanocatalysts and over 2.5 folds of enhancement can be achieved.A volcano plot is derived to describe the relationship between the catalytic activities and gap size of the PGN nanocatalysts,which is well explained by the interplay of their light harvesting and charge transport capabilities.These results highlight the importance of gap engineering in PGNs for plasmonic catalysis and offer the promise of developing efficient plasmonic nanocatalysts for other heterogeneous catalytic reactions.

Elemental composition and risk assessment of heavy metals in the PM10 fractions of road dust and roadside soil

A total of 64 dust samples were analyzed to determine the size distribution and elemental composition of the PM10 fraction, including42 road dust(RD), 12 roadside soil(RSD), and 10 park road dust(PRD) samples. The mass of dust smaller than 20μm was dominated by particles sized 2.5-16 μm, which accounted for 85%, 88%, and 87% of the RD, PRD, and RSD, respectively. Additionally, crustal elements accounted for 30.14%, 36.35%, and 37.14% of the PMio fractions of the RD, RSD, and PRD, respectively. The most abundant trace elements in RD, RSD, and PRD were Zn, Mn, and Cu (range, 277 to 874 mg/kg). Moreover, the /geo values revealed all dusts were contaminated with Pb, Zn, Cu, Sb, Sn, and Cd. Health risk assessment showed that Mn, Ni, Cu, Zn, Cd, Sb, and Pb in the PM10 fraction of three types of dusts posed non-cancer risks to children but posed no non-cancer risk to adults. Additionally, As, Ni, and Cd posed no cancer risk to inhabitants.

Growth kinetics of titanium boride layers on the surface of Ti6Al4V

Dual titanium boride layers consisting of continuous TiB2 top-layer and TiB whisker sub- layer were formed on the surface of Ti6Al4V alloy using powder-pack boriding technique. An iso-thickness diagram of the whole boride layer was fitted with the data of thickness of the coating, treatment time and process temperature using Sigma Plot10.0 software. Growth kinetics of the titanium boride layer were analyzed by measuring the extent of penetration of TiB2 and TiB whisker as a function of boriding time in the range of 5-20 h and boriding temperature in the range of 1000-1100 ℃. By the linear regression analysis of growth kinetics of titanium boride layer, the diffusivity K and average diffusion activation energy （Q） of boron atoms in Ti6Al4V alloy were calculated, respectively.

Smartphones for sensing

简单、便携式的分析设备为个人照顾，临床的分析，在食物的变应原察觉，并且环境监视正在进入我们的每日的生活。Smartphones 最流行的 state-of-art 移动设备，为察觉到应用有显著潜力。physical-co-chemical 传感器的一个成长集合被嵌入；这些包括存取并且表现数据分析的加速表，麦克风，照相机，回转仪，和 GPS 单位。在这评论，我们讨论集中于包括代表性的电磁的、听觉的频率察觉到的 smartphone 的最近的工作，光、电气化学的传感器。这些能力的发展将以他们的表演导致更紧缩、小、划算、灵活、持久的设备。