2,294 research outputs found
From Si Towards SiC Technology for Harsh Environment Sensing
No full textIn the coming decade, the development in the area of More than Moore will certainly take over from Moore’s Law. Sensor development and sensor integration will prevail above lower node development. New packaging solutions will be developed which will fuel the integration of sensors. These developments can still be silicon based but where harsh environments are involved wide-bandgap (WBG) materials, such as gallium nitride (GaN) or silicon carbide (SiC), will take over the development efforts spend. In this chapter, the use of WBG SiC material is discussed and reviewed towards possible applications for sensing under harsh environment exposure.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and Material
Precision in harsh environments
No full textMicrosystems are increasingly being applied in harsh and/or inaccessible environments, but many markets expect the same level of functionality for long periods of time. Harsh environments cover areas that can be subjected to high temperature, (bio)-chemical and mechanical disturbances, electromagnetic noise, radiation, or high vacuum. In the field of actuators, the devices must maintain stringent accuracy specifications for displacement, force, and response times, among others. These new requirements present additional challenges in the compensation for or elimination of cross-sensitivities. Many state-of-the-art precision devices lose their precision and reliability when exposed to harsh environments. It is also important that advanced sensor and actuator systems maintain maximum autonomy such that the devices can operate independently with low maintenance. The next-generation microsystems will be deployed in remote and/or inaccessible and harsh environments that present many challenges to sensor design, materials, device functionality, and packaging. All of these aspects of integrated sensors and actuator microsystems require a multidisciplinary approach to overcome these challenges. The main areas of importance are in the fields of materials science, micro/nano-fabrication technology, device design, circuitry and systems, (first-level) packaging, and measurement strategy. This study examines the challenges presented by harsh environments and investigates the required approaches. Examples of successful devices are also given
Surface-micromachined Silicon Carbide Pirani Gauges for Harsh Environments
No full textThe application of pressure sensors in harsh environments is typically hindered by the stability of the material over long periods of time. This work focuses on the design and fabrication of surface micromachined Pirani gauges which are designed to be compatible with state-of-the-art Silicon Carbide CMOS technology. Such an integrated platform would boost harsh environment compatibility while reducing the required packaging complexity. An analytical model was derived describing the design variables of the Pirani gauges followed by Finite Element Analysis. The Pirani gauges were fabricated in a CMOS compatible cleanroom with a process employing only three masks, thus suitable for mass production. The SiC-based Pirani gauge is far more competitive than the traditional Si-based Pirani gauge in terms of endurance in high-temperature environments. From 25°C to 650°C, the gauge shows a reproducible response to pressure changes and has a maximum sensitivity of /Pa at room temperature, and of /Pa at 650°C. Additionally, some of the gauges were demonstrated to operate at temperatures up to 750°C.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and MaterialsQN/Zandbergen La
Manifold: a multimodal generic user interface
No full textA User Interface (UI) is generally tightly coupled to the business logic of the application, and a great deal of modification is required to model it to separate the application logic. Manifold is an answer to such an issue. It offers a generic user interface framework where different application designers could develop separate application logic using the same Manifold front-end. Manifold employs the Model-View-Controller (MVC) design pattern to achieve its generic nature by providing separation of concerns between the UI and the application domain. The event frame concept incorporated on Manifold allows translation of user events to operations on application data via a central Controller object. The Controller object connects the Manifold front-end to the back-end application domain. This approach highly expedites the development of new features on the user interface, which remains decoupled from the rest of the application. It also allows building different applications on different servers and visualizing them on the Manifold UI. This thesis focuses on the enhancement of the Manifold framework both from the UI- and application-development perspective. New features based on industry standards are incorporated and the shortcomings present in the previous versions are eliminated to enhance the user-experience with Manifold. The flexibility of the Manifold framework allows development of applications with separate application logic and attaches them directly with the Manifold UI. The thesis developed applications and algorithms to visualize Manifold objects as fields in a relational database. The relational database approach allows saving the UI objects into a hierarchical data structure, rather than saving them as such on the file system. This provides added benefits of persistent information about objects, allowing data-analysis to be performed on them at various steps. This approach allowed extending the use of Manifold to areas such as text-, pattern- and speech recognition. Text recognition allows user to generate graphical objects (“glyphs”) on Manifold by typing in plain text data. Pattern recognition allows providing users with visual feedback if a collection of graphics in Manifold could be recognized as a particular pattern class. Speech Recognition allows the user to issue commands to the Manifold UI to perform specific tasks, which otherwise require manual manipulation. The newly developed features are analyzed for their structural and code complexity with direct repercussions to their re-use in future designs and performance optimization obtained by employing the best software engineering practices. The new features are evaluated with respect to their performance in the Manifold framework.M.S.Includes bibliographical referencesby Harsh Yada
A new framework of optimizing keyword weights in text categorization and record querying
No full textIn text mining research, the Vector Space Model (VSM) has been commonly used to represent text documents as a vector where each component is associated with a particular word in the documents. Assigning appropriate keyword weights in VSM has been critical in Information Retrieval (IR) and Text Categorization (TC).
Traditionally keyword weighting processes are unsupervised; that is, the knowledge of document's category is not leveraged to label the documents. Typically, each keyword weight is assigned using the term frequency -- inverse document frequency (TFIDF) measure. Although the TFIDF measure has been proven effective in several text mining problems, it might not give the optimal classification power for IR and TC. In this thesis, we propose a new optimization framework to find the best keyword weights based on the proposed inter-class and intra-class similarity concept.
The optimal keyword weight can be viewed as the feature space projection where documents from the same category are best clustered together and separated from other categories. Subsequently, the category average (centroid) classification is employed to categorize text documents. The proposed approach is tested on two practical applications: record query and text categorization. The record query application is slightly different from traditional IR problems as the goal is to find correlated (duplicate and master) text records. This problem was initiated by a telecommunication company where service engineers attempt to look for associations of the current defect problem in previously recorded problems in the database. Extensive experiments demonstrate that the proposed framework significantly improves the classification accuracy and provides balanced performance as measured on all text categories when compared to the standard TFIDF search. The text categorization application is tested on the Reuters news data set which is a gold-standard benchmark data set. The results show that our framework improves performance for the two applications considered, namely Information Retrieval and Text Categorization.M.S.Includes bibliographical references (p. 80-83)
Design and Characterization of a Data Converter in a SiC CMOS Technology for Harsh Environment Sensing Applications
No full textThis work presents the design and characterization of an analog-to-digital converter (ADC) with silicon carbide (SiC) for sensing applications in harsh environments. The SiC-based ADC is implemented with the state-of-the-art low-voltage SiC complementary-metal-oxide-semiconductor (CMOS) technology developed by Fraunhofer IISB. Two types of ADCs, i.e., a 4-bit flash ADC and a 6-bit successive-approximation (SAR) ADC, are designed and simulated up to 300 degrees Celsius. The measurement results show that the 4-bit SiC flash ADC can operate reliably up to at least 200 degrees Celsius, which outperforms the Si counterpart regarding the maximum operating temperature.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and MaterialsMicroelectronic
Time-series clustering for pattern recognition of speed and heart rate while driving: A magnifying lens on the seconds around harsh events
No full textDriving pattern recognition has been applied for the purposes of driving styles identification and harsh driving events detection. However, the evolution of driving behavior around and especially before such events has not been investigated at a microscopic level. The objective of this research is to reveal existing driving patterns around harsh events at the driving ‘pulse’ level i.e. a few seconds before and after the event. For that purpose, a time-series clustering approach is applied on speed and heart rate metrics of individual drivers using data collected from a large naturalistic driving study. Results show that there are distinct speed patterns before harsh braking, harsh acceleration, and harsh cornering events. A deceleration is identified shortly before most harsh acceleration and cornering events, which possibly indicates reckless behavior, i.e. drivers not dedicating enough time to smoothly brake before cornering, or of a brief ‘decision-making’ moment before the harsh manoeuvre. On the contrary, speed seems to be steady before harsh braking events. Regarding heart rate, the analysis revealed certain patterns only after raw data were cleansed and filtered. These patterns may show increasing, decreasing or variable heart rate trends, which may correspond to different stress patterns of drivers around harsh events. Finally, we introduce the concept of driving pattern consistency, which can reveal the share of individual drivers that follow the same harsh event pattern. It is indicated that more than half of the drivers are not consistent, suggesting that driving patterns around harsh events may be more context-related than driver personality-related.Policy & StrategySafety and Security Scienc
Degradation of bisphenol-a-polycarbonate (BPA-PC) optical lenses under simulated harsh environment conditions
No full textThis paper investigates degradation and failure mechanisms of BPA-PC lenses in simulated harsh environment conditions. Exposure of secondary optics in Light Emitting Diode LED-based systems or any other similar applications to environmental stresses can adversely effect the performance and lifetime of products. This paper simulates a harsh environment condition, using a salt bath oven. Salt spray exposure/ageing tests at 45° C were carried out up to four months. Fourier transform infrared-attenuated total reflection FTIR-ATR spectrometer and Lambda 950 Ultraviolet-Visible (UV-VIS) spectrophotometer were used to study the optical and chemical characteristics of aged plates. Results showed that salt bath exposure test resulted in the severe deterioration of optical characteristics BPA-PC samples. Degradation of optical properties of BPA-PC plates is attributable to the oxidation of samples.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and Material
Silicon carbide reinforced vertically aligned carbon nanotube composite for harsh environment mems
No full textFabricating high-aspect-ratio (HAR) structures with silicon carbide (SiC) is a challenging task. This paper presents a silicon carbide (SiC) reinforced vertically aligned carbon nanotubes (VACNT) composite as a promising candidate to fabricate HAR MEMS devices for harsh environment applications. The use of a VACNT array allows the fast realization of HAR structures as a template for MEMS fabrication. The template can later be easily filled by amorphous-SiC due to the porous nature of the VACNT forest. The SiC-CNT nanocomposite has electrical properties dominated by VACNT arrays and mechanical stability dominated by the a-SiC. Based on this concept, a thermal actuator is fabricated and proven to function up to 450°C for the first time.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Electronic Components, Technology and MaterialsSupport EK
Hostile causal attributions and harsh parenting: parent age as a moderating factor
No full text2016 Summer.Includes bibliographical references.Adolescent mothers tend to be more at risk for harsh parenting than older mothers. Parent processes such as stress, hostile causal attributions, and anger are also linked to harsh parenting. In this study, adolescent mothers, former adolescent mothers, and older mothers (N=589) were compared and the links between hostile causal attributions and stress and harsh parenting were examined. Age of the mother was looked at as a moderator in these relations. Mediational pathways between stress, anger, and harsh parenting and hostile causal attributions, anger, and harsh parenting were also examined. Results indicate that adolescent mothers are more alike than different from older mothers. In all groups, stress and hostile causal attributions were predictive of harsh parenting, and correlational analyses indicated that anger mediated these pathways. However, when baseline preference for harsh punishment was taken into account, anger no longer mediated any of the pathways. This indicates that baseline preference for harsh punishment may be the most significant predictor of late punishment. The only pathway moderated by age was between parent-blaming attributions and harsh parenting in that older mothers were more likely to parent harshly in the presence of parent-blaming attributions than younger mothers. These findings have implications for prevention and intervention programs and may shift focus from age of the parent to the parenting processes of stress, hostile causal attributions, and anger management
- …
