Energy big data: A survey <s> C. CROWD-SOURCED DATA CONTROL <s> Modern machine learning-based approaches to computer vision require very large databases of hand labeled images. Some contemporary vision systems already require on the order of millions of images for training (e.g., Omron face detector [9]). New Internet-based services allow for a large number of labelers to collaborate around the world at very low cost. However, using these services brings interesting theoretical and practical challenges: (1) The labelers may have wide ranging levels of expertise which are unknown a priori, and in some cases may be adversarial; (2) images may vary in their level of difficulty; and (3) multiple labels for the same image must be combined to provide an estimate of the actual label of the image. Probabilistic approaches provide a principled way to approach these problems. In this paper we present a probabilistic model and use it to simultaneously infer the label of each image, the expertise of each labeler, and the difficulty of each image. On both simulated and real data, we demonstrate that the model outperforms the commonly used "Majority Vote" heuristic for inferring image labels, and is robust to both noisy and adversarial labelers. <s> BIB001 </s> Energy big data: A survey <s> C. CROWD-SOURCED DATA CONTROL <s> Mobile phones are becoming increasingly sophisticated with a rich set of on-board sensors and ubiquitous wireless connectivity. However, the ability to fully exploit the sensing capabilities on mobile phones is stymied by limitations in multimedia processing techniques. For example, search using cellphone images often encounters high error rate due to low image quality. In this paper, we present CrowdSearch, an accurate image search system for mobile phones. CrowdSearch combines automated image search with real-time human validation of search results. Automated image search is performed using a combination of local processing on mobile phones and backend processing on remote servers. Human validation is performed using Amazon Mechanical Turk, where tens of thousands of people are actively working on simple tasks for monetary rewards. Image search with human validation presents a complex set of tradeoffs involving energy, delay, accuracy, and monetary cost. CrowdSearch addresses these challenges using a novel predictive algorithm that determines which results need to be validated, and when and how to validate them. CrowdSearch is implemented on Apple iPhones and Linux servers. We show that CrowdSearch achieves over 95% precision across multiple image categories, provides responses within minutes, and costs only a few cents. <s> BIB002 </s> Energy big data: A survey <s> C. CROWD-SOURCED DATA CONTROL <s> Harnessing a crowd of Web users for data collection has recently become a wide-spread phenomenon. A key challenge is that the human knowledge forms an open world and it is thus difficult to know what kind of information we should be looking for. Classic databases have addressed this problem by data mining techniques that identify interesting data patterns. These techniques, however, are not suitable for the crowd. This is mainly due to properties of the human memory, such as the tendency to remember simple trends and summaries rather than exact details. Following these observations, we develop here for the first time the foundations of crowd mining. We first define the formal settings. Based on these, we design a framework of generic components, used for choosing the best questions to ask the crowd and mining significant patterns from the answers. We suggest general implementations for these components, and test the resulting algorithm's performance on benchmarks that we designed for this purpose. Our algorithm consistently outperforms alternative baseline algorithms. <s> BIB003 </s> Energy big data: A survey <s> C. CROWD-SOURCED DATA CONTROL <s> In emerging Big Data scenarios, obtaining timely, high-quality answers to aggregate queries is difficult due to the challenges of processing and cleaning large, dirty data sets. To increase the speed of query processing, there has been a resurgence of interest in sampling-based approximate query processing (SAQP). In its usual formulation, however, SAQP does not address data cleaning at all, and in fact, exacerbates answer quality problems by introducing sampling error. In this paper, we explore an intriguing opportunity. That is, we explore the use of sampling to actually improve answer quality. We introduce the Sample-and-Clean framework, which applies data cleaning to a relatively small subset of the data and uses the results of the cleaning process to lessen the impact of dirty data on aggregate query answers. We derive confidence intervals as a function of sample size and show how our approach addresses error bias. We evaluate the Sample-and-Clean framework using data from three sources: the TPC-H benchmark with synthetic noise, a subset of the Microsoft academic citation index and a sensor data set. Our results are consistent with the theoretical confidence intervals and suggest that the Sample-and-Clean framework can produce significant improvements in accuracy compared to query processing without data cleaning and speed compared to data cleaning without sampling. <s> BIB004
Although various technologies can be applied for different data processing periods, some vital data management and analysis tasks in the power system cannot be addressed completely by data processing technologies. However, these hard tasks such as entity resolution, sentiment analysis, and image recognition, can be dealt with human cognitive ability BIB002 . Generally, utilizing the capabilities of the crowd is an effective method to handle computer-hard tasks in the power system. Therefore, crowd-sourced data management has aroused increasing attention in energy big data research, such as data integration BIB001 , knowledge construction BIB003 , data cleaning BIB004 , etc. In the energy domain, widespread sensor nodes are the same as workers in crowd-sourced data control. As workers being task operators, sensor nodes are always assigned to deal with diverse data collected from power grid. Problems in crowd-sourced data control can be divided into two groups: quality control and cost control. The quality control is the most important because crowd-sourcing often generated relatively low-quality results or even noise. Thus, we will analyze quality control in detail.