When Crowdsourcing Meets Data Markets:A Fair Data Value Metric for Data Trading

Large-quantity and high-quality data is critical to the success of machine learning in diverse applications.Faced with the dilemma of data silos where data is difficult to circulate,emerging data markets attempt to break the dilemma by facilitating data exchange on the Internet.Crowdsourcing,on the other hand,is one of the important methods to efficiently collect large amounts of data with high-value in data markets.In this paper,we investigate the joint problem of efficient data acquisition and fair budget distribution across the crowdsourcing and data markets.We propose a new metric of data value as the uncertainty reduction of a Bayesian machine learning model by integrating the data into model training.Guided by this data value metric,we design a mechanism called Shapley Value Mechanism with Individual Rationality(SV-IR),in which we design a greedy algorithm with a constant approximation ratio to greedily select the most cost-efficient data brokers,and a fair compensation determination rule based on the Shapley value,respecting the individual rationality constraints.We further propose a fair reward distribution method for the data holders with various effort levels under the charge of a data broker.We demonstrate the fairness of the compensation determination rule and reward distribution rule by evaluating our mechanisms on two real-world datasets.The evaluation results also show that the selection algorithm in SV-IR could approach the optimal solution,and outperforms state-of-the-art methods.

An Empirical Study on Automated Test Generation Tools for Java:Effectiveness and Challenges

Automated test generation tools enable test automation and further alleviate the low efficiency caused by writing hand-crafted test cases.However,existing automated tools are not mature enough to be widely used by software testing groups.This paper conducts an empirical study on the state-of-the-art automated tools for Java,i.e.,EvoSuite,Randoop,JDoop,JTeXpert,T3,and Tardis.We design a test workflow to facilitate the process,which can automatically run tools for test generation,collect data,and evaluate various metrics.Furthermore,we conduct empirical analysis on these six tools and their related techniques from different aspects,i.e.,code coverage,mutation score,test suite size,readability,and real fault detection ability.We discuss about the benefits and drawbacks of hybrid techniques based on experimental results.Besides,we introduce our experience in setting up and executing these tools,and summarize their usability and user-friendliness.Finally,we give some insights into automated tools in terms of test suite readability improvement,meaningful assertion generation,test suite reduction for random testing tools,and symbolic execution integration.

Gfarm/BB——Gfarm File System for Node-Local Burst Buffer

Burst buffer has become a major component to meet the I/O performance requirement of HPC bursty traffic.This paper proposes Gfarm/BB that is a file system for a burst buffer efficiently exploiting node-local storage systems.Although node-local storages improve storage performance,they are only available during the job allocation.Gfarm/BB should have better access and metadata performance while it should be constructed on-demand before the job execution.To improve the read and write performance,it exploits the file descriptor passing and remote direct memory access(RDMA).It improves the metadata performance by omitting the persistency and the redundancy since it is a temporal file system.Using RDMA,writes and reads bandwidth are improved by 1.7x and 2.2x compared with IP over InfiniBand(IPoIB),respectively.It achieves 14700 operations per second in the directory creation performance,which is 13.4x faster than the fully persistent and redundant case.The construction of Gfarm/BB takes 0.31 seconds using 2 nodes.IOR benchmark and ARGOT-IO application I/O benchmark show the scalable performance improvement by exploiting the locality of node-local storages.Compared with BeeOND,Gfarm/BB shows 2.6x and 2.4x better performance in IOR write and read benchmarks,respectively,and it shows 2.5x better performance in ARGOT-IO.

Assisting Visually Impaired People to Acquire Targets on a Large Wall-Mounted Display

Large displays have become ubiquitous in our everyday lives, but these displays are designed for sighted people.This paper addresses the need for visually impaired people to access targets on large wall-mounted displays. We developed an assistive interface which exploits mid-air gesture input and haptic feedback, and examined its potential for pointing and steering tasks in human computer interaction（HCI）. In two experiments, blind and blindfolded users performed target acquisition tasks using mid-air gestures and two different kinds of feedback（i.e., haptic feedback and audio feedback）. Our results show that participants perform faster in Fitts＇ law pointing tasks using the haptic feedback interface rather than the audio feedback interface. Furthermore, a regression analysis between movement time（MT） and the index of difficulty（ID）demonstrates that the Fitts＇ law model and the steering law model are both effective for the evaluation of assistive interfaces for the blind. Our work and findings will serve as an initial step to assist visually impaired people to easily access required information on large public displays using haptic interfaces.

Designing Motion Gesture Interfaces in Mobile Phones for Blind People

Despite the existence of advanced functions in smartphones, most blind people are still using old-fashioned phones with familiar layouts and dependence on tactile buttons. Smartphones support accessibility features including vibration, speech and sound feedback, and screen readers. However, these features are only intended to provide feedback to user commands or input. It is still a challenge for blind people to discover functions on the screen and to input the commands. Although voice commands are supported in smartphones, these commands are difficult for a system to recognize in noisy environments. At the same time, smartphones are integrated with sophisticated motion sensors, and motion gestures with device tilt have been gaining attention for eyes-free input. We believe that these motion gesture interactions offer more efficient access to smartphone functions for blind people. However, most blind people are not smartphone users and they are aware of neither the affordances available in smartphones nor the potential for interaction through motion gestures. To investigate the most usable gestures for blind people, we conducted a user-defined study with 13 blind participants. Using the gesture set and design heuristics from the user study, we implemented motion gesture based interfaces with speech and vibration feedback for browsing phone books and making a call. We then conducted a second study to investigate the usability of the motion gesture interface and user experiences using the system. The findings indicated that motion gesture interfaces are more efficient than traditional button interfaces. Through the study results, we provided implications for designing smartphone interfaces.

FIFA的第二次入侵

大概从今年年初开始，我们在媒体上看到的足球题材网络游戏渐渐多了起来，根据笔者的不完全统计，目前正在开发和即将运营的类似游戏起码也有10款了。这些游戏以休闲风格居多，就像《街头篮球》一样，多以真实游戏结合技能的购买和使用特色，显然这类游戏并不足以吸引所有喜欢篮球或足球的潜在用户群。所以，当传说中的FIFA Online即将进入中国时，那些忠实的FIFA游戏Fans一定会由衷地兴奋起来。

观点有感

在E3和TGS一个压缩一个合并的大背景下，明年的ChinaJoy也许真正可以喊出“世界规模最大的游戏展”之类的口号了。或许生活在这个时代的中国玩家是幸福的，他们已经不用像10年前的前辈玩家们的端着几本私下流传，印刷低劣的攻略书整天做白日梦（那时很多根本没有游戏机），他们想看的现在网络上都可以看到。