Characterizing and Detecting Duplicate Logging Code Smells

Developers rely on software logs for a wide variety of tasks, such as debugging, testing, program comprehension, verification, and performance analysis. Despite the importance of logs, prior studies show that there is no industrial standard on how to write logging statements. Recent research on logs often only considers the appropriateness of a log as an individual item (e.g., one single logging statement); while logs are typically analyzed in tandem. In this thesis, we focus on studying duplicate logging statements, which are logging statements that have the same static text message. Such duplications in the text message are potential indications of logging code smells, which may affect developers’ understanding of the dynamic view of the system. We manually studied over 3K duplicate logging statements and their surrounding code in four large-scale open source systems: Hadoop, CloudStack, ElasticSearch, and Cassandra. We uncovered five patterns of duplicate logging code smells. For each instance of the code smell, we further manually identify the problematic (i.e., require fixes) and justifiable (i.e., do not require fixes) cases. Then, we contact developers in order to verify our manual study result. We integrated our manual study result and developers’ feedback into our automated static analysis tool, DLFinder, which automatically detects problematic duplicate logging code smells. We evaluated DLFinder on the four manually studied systems and four additional systems: Kafka, Flink, Camel and Wicket. In total, combining the results of DLFinder and our manual analysis, we reported 91 problematic code smell instances to developers and all of them have been fixed. This thesis provides an initial step on creating a logging guideline for developers to improve the quality of logging code. DLFinder is also able to detect duplicate logging code smells with high precision and recall

Tooling ball detecting method design for ABB welding robot in automatic TIG welding process

This thesis provides the design process for a new tooling ball detection method to calibrate moulds in automatic TIG welding. A mechanical component is designed to locate the tooling ball and convert the position information into analog signals. An electrical component is designed to process signals from the mechanical component and achieve the signal communication process. Finally, the computational component is designed and programmed to receive bits from the electrical component and convert information into position values for the tooling ball. The homogeneous transformation process is mathematically modeled for position computation in a robot system. The method is significantly different from current methods that have been developed and applied. Firstly, it uses a mechanical-touch style operation to locate the tooling ball with only a one-time detection operation. Secondly, it introduces a new approach for utilizing the joystick. Rather than as a manually operated direction controller for mobile control of devices, the joystick is used as a passive detection angle sensor. In order to properly use the joystick as an angle sensor, the joystick calibration method is also designed and tested. The designs of the three components are all implemented and tested separately. The results of these tests prove the feasibility of the new detecting method; however, the accuracy of detection is not yet acceptable and further improvements need to be made. In addition, a vision-based detecting method is also discussed at the end of the thesis. Compared to mechanical touch-style detection, the vision-based detecting method is designed to obtain better performance in a high temperature environment and to automate the tooling ball detecting process

Towards Providing Automated Supports to Developers on Making Logging Decisions and Log Analysis

Due to the lack of practical guidelines on how to write logging statements and large volume of logs routinely generated by software products, how to make proper logging decisions and efficiently analyze the logs are challenging in practice. In this thesis, we focus on these two main challenges and propose a series of approaches to address the problem and help developers on logging practices in two aspects: (1) assist in making logging decisions and (2) assist in log analysis. For logging decisions, we tackle the challenge by providing suggestions on writing logging statements. We first provide suggestions for logging locations. We find that our models are effective in suggesting logging locations at the block level. We then study the verbosity levels in the logging statements. We propose a deep learning based approach that can leverage the ordinal nature of log levels to make suggestions on choosing log levels. Our approach outperforms the baseline approaches and are effective at suggesting log levels. Finally, we investigate practitioners' expectation on the readability of log messages by conducting a series of semi-structured interviews with industrial practitioners. We derive three aspects that are related to the readability of log messages. We also explore the potential of automatically classifying the readability of log messages and find that both deep learning and machine learning approaches is effective at such classifications. For log analysis, we focus on studying log abstraction, which is a crucial step for automated log analysis. We find that different categories of dynamic variables in logs record valuable information that can be important for different tasks, such information is abstracted by prior log abstraction techniques. We propose a deep learning based log abstraction approach, which can identify different categories of dynamic variables and abstract specified categories. Our approach outperforms state-of-the-art log abstraction techniques on general log abstraction and also achieves promising results on variable-aware log abstraction. We also find that variable-aware log abstraction can help improve the performance of log-based anomaly detection

Internal waves in 2D domains with ergodic classical dynamics

We study a model of internal waves in an effectively 2D aquarium under periodic forcing. In the case when the underlying classical dynamics has sufficiently irrational rotation number, we prove that the energy of the internal waves remains bounded. This involves studying the spectrum of a related 0-th order pseudodifferential operator at spectral parameters corresponding to such dynamics. For the special cases of rectangular and elliptic domains, we give an explicit spectral description of that operator.Comment: 19 pages, 4 figure

Fabrication of Capacitive Micromachined Ultrasonic Transducers based on Adhesive Wafer Bonding

Capacitive micromachined ultrasonic transducers (CMUTs) can be used for medical imaging, non-destructive testing or medical treatment applications. It can also be used as gravimetric sensors for gas sensing or immersion bio-sensing. Although various CMUT fabrication methods have been reported, there are still many challenges to address. Conventional fabrication methods can be categorized as either surface micromachining or the wafer bonding method. These methods have design trade-offs and limitations associated with process complexity, structural parameter optimization and wafer materials selection. For example, surface micromachining approaches can suffer from complicated fabrication processes. In addition, structural parameters cannot be fully optimized due to feasibility concerns during fabrication. In contrast, the development of wafer bonding techniques enabled CMUTs to be fabricated in a straightforward way and structural parameters can be easily optimized when compared with a surface micromachining approach. However, the yield of the traditional wafer bonded CMUTs is very sensitive to contaminations and the surface quality at the bonding interface. Although the difficulties of the wafer bonding process are not always reported, they definitely exist for every researcher who wants to fabricate their own CMUTs. As a result, this dissertation work aims to develop a CMUT fabrication process with fewer fabrication constraints, low-cost and low process temperature for CMOS integration. The developed CMUT fabrication processes reported in the thesis applied photosensitive polymer adhesive for wafer bonding in order to make a process with good tolerance to contaminations and defects on the wafer surface, present a wide range of material selection at the bonding interface and require low process temperature (less than 250°C). These features can benefit CMUT fabrication with increased yield better design flexibility and lower cost. Having maximum process temperature of 250°C, the developed processes can also be CMOS compatible. Furthermore, a novel CMUT structure, which can only be achieved by the reported technique, was developed showing more than doubled ultrasound receive sensitivity when compared with conventional CMUT structures. The fabrication processes were developed systematically and the details of process development will be presented in this thesis

Determination of Optimal Opening Scheme for Electromagnetic Loop Networks Based on Fuzzy Analytic Hierarchy Process

Studying optimization and decision for opening electromagnetic loop networks plays an important role in planning and operation of power grids. First, the basic principle of fuzzy analytic hierarchy process (FAHP) is introduced, and then an improved FAHP-based scheme evaluation method is proposed for decoupling electromagnetic loop networks based on a set of indicators reflecting the performance of the candidate schemes. The proposed method combines the advantages of analytic hierarchy process (AHP) and fuzzy comprehensive evaluation. On the one hand, AHP effectively combines qualitative and quantitative analysis to ensure the rationality of the evaluation model; on the other hand, the judgment matrix and qualitative indicators are expressed with trapezoidal fuzzy numbers to make decision-making more realistic. The effectiveness of the proposed method is validated by the application results on the real power system of Liaoning province of China