Scan-Chain Intra-Cell Aware Testing

This paper first presents an evaluation of the effectiveness of different test pattern sets in terms of ability to detect possible intra-cell defects affecting the scan flip-flops. The analysis is then used to develop an effective test solution to improve the overall test quality. As a major result, the paper demonstrates that by combining test vectors generated by a commercial ATPG to detect stuck-at and delay faults, plus a fragment of extra test patterns generated to specifically target the escaped defects, we can obtain a higher intra-cell defect coverage (i.e., 6.46% on average) and a shorter test time (i.e., 42.20% on average) than by straightforwardly using an ATPG which directly targets these defects

Roving vehicle motion control Quarterly report, 1 Mar. - 31 May 1967

System and subsystem requirements for remote control of roving space vehicle motio

Advanced Network Inference Techniques Based on Network Protocol Stack Information Leaks

Side channels are channels of implicit information flow that can be used to find out information that is not allowed to flow through explicit channels. This thesis focuses on network side channels, where information flow occurs in the TCP/IP network stack implementations of operating systems. I will describe three new types of idle scans: a SYN backlog idle scan, a RST rate-limit idle scan, and a hybrid idle scan. Idle scans are special types of side channels that are designed to help someone performing a network measurement (typically an attacker or a researcher) to infer something about the network that they are not otherwise able to see from their vantage point. The thesis that this dissertation tests is this: because modern network stacks have shared resources, there is a wealth of information that can be inferred off-path by both attackers and Internet measurement researchers. With respect to attackers, no matter how carefully the security model is designed, the non-interference property is unlikely to hold, i.e., an attacker can easily find side channels of information flow to learn about the network from the perspective of the system remotely. One suggestion is that trust relationships for using resources be made explicit all the way down to IP layer with the goal of dividing resources and removing sharendess to prevent advanced network reconnaissance. With respect to Internet measurement researchers, in this dissertation I show that the information flow is rich enough to test connectivity between two arbitrary hosts on the Internet and even infer in which direction any blocking is occurring. To explore this thesis, I present three research efforts: --- First, I modeled a typical TCP/IP network stack. The building process for this modeling effort led to the discovery of two new idles scans: a SYN backlog idle scan and a RST rate-limited idle scan. The SYN backlog scan is particularly interesting because it does not require whoever is performing the measurements (i.e., the attacker or researcher) to send any packets to the victim (or target) at all. --- Second, I developed a hybrid idle scan that combines elements of the SYN backlog idle scan with Antirez\u27s original IPID-based idle scan. This scan enables researchers to test whether two arbitrary machines in the world are able to communicate via TCP/IP, and, if not, in which direction the communication is being prevented. To test the efficacy of the hybrid idle scan, I tested three different kinds of servers (Tor bridges, Tor directory servers, and normal web servers) both inside and outside China. The results were congruent with published understandings of global Internet censorship, demonstrating that the hybrid idle scan is effective. --- Third, I applied the hybrid idle scan to the difficult problem of characterizing inconsistencies in the Great Firewall of China (GFW), which is the largest firewall in the world. This effort resolved many open questions about the GFW. The result of my dissertation work is an effective method for measuring Internet censorship around the world, without requiring any kind of distributed measurement platform or access to any of the machines that connectivity is tested to or from

Improving timing verification and delay testing methodologies for IC designs

textThe task of ensuring the correct temporal behavior of IC designs, both before and after fabrication, is extremely important. It is becoming even more imperative as the demand for performance increases and process technology advances into the deep sub-micron region. This dissertation tackles the key issues in the timing verification and delay testing methodologies. An efficient methodology is presented to identify false timing paths in the timing verification methodology which utilizes ATPG technique and timing information from an ordered list of timing paths according to the delay information. This dissertation also presents a speed binning methodology which utilizes structural delay tests successfully instead of functional tests. In addition, it establishes a methodology which quantifies the correlation between the timing verification prediction and actual silicon measurement of timing paths. This quantification methodology lays the foundation for further research to study the impact of deep submicron effects on design performanceElectrical and Computer Engineerin

Universal in vivo Textural Model for Human Skin based on Optical Coherence Tomograms

Currently, diagnosis of skin diseases is based primarily on visual pattern recognition skills and expertise of the physician observing the lesion. Even though dermatologists are trained to recognize patterns of morphology, it is still a subjective visual assessment. Tools for automated pattern recognition can provide objective information to support clinical decision-making. Noninvasive skin imaging techniques provide complementary information to the clinician. In recent years, optical coherence tomography has become a powerful skin imaging technique. According to specific functional needs, skin architecture varies across different parts of the body, as do the textural characteristics in OCT images. There is, therefore, a critical need to systematically analyze OCT images from different body sites, to identify their significant qualitative and quantitative differences. Sixty-three optical and textural features extracted from OCT images of healthy and diseased skin are analyzed and in conjunction with decision-theoretic approaches used to create computational models of the diseases. We demonstrate that these models provide objective information to the clinician to assist in the diagnosis of abnormalities of cutaneous microstructure, and hence, aid in the determination of treatment. Specifically, we demonstrate the performance of this methodology on differentiating basal cell carcinoma (BCC) and squamous cell carcinoma (SCC) from healthy tissue

Micromachined Scanning Devices for 3D Acoustic Imaging

Acoustic imaging (including ultrasound and photoacoustic imaging) refers to a class of imaging methods that use high-frequency sound (ultrasound) waves to generate contrast images for the interrogated media. It provides 3D spatial distribution of structural, mechanical, and even compositional properties in different materials. To conduct 3D ultrasound imaging, 2D ultrasound transducer arrays followed by multi-channel high-frequency data acquisition (DAQ) systems are frequently used. However, as the quantity and density of the transducer elements and also the DAQ channels increase, the acoustic imaging system becomes complex, bulky, expensive, and also power consuming. This situation is especially true for 3D imaging systems, where a 2D transducer array with hundreds or even thousands of elements could be involved. To address this issue, the objective of this research is to achieve new micromachined scanning devices to enable fast and versatile 2D ultrasound signal acquisition for 3D image reconstruction without involving complex physical transducer arrays and DAQ electronics. The new micromachined scanning devices studied in this research include 1) a water-immersible scanning mirror microsystem, 2) a micromechanical scanning transducer, and 3) a multi-layer linear transducer array. Especially, the water-immersible scanning mirror microsystem is capable of scanning focused ultrasound beam (from a single-element transducer) in two dimensions for 3D high-resolution acoustic microscopy. The micromechanical scanning transducer is capable of sending and receiving ultrasound signal from a single-element transducer to a 2D array of locations for 3D acoustic tomography. The multi-layer linear transducer array allows a unique electronic scanning scheme to simulate the functioning of a much larger 2D transducer array for 3D acoustic tomography. The design, fabrication and testing of the above three devices have been successfully accomplished and their applications in 3D acoustic microscopy and tomography have been demonstrated

Micromachined Scanning Devices for 3D Acoustic Imaging

Acoustic imaging (including ultrasound and photoacoustic imaging) refers to a class of imaging methods that use high-frequency sound (ultrasound) waves to generate contrast images for the interrogated media. It provides 3D spatial distribution of structural, mechanical, and even compositional properties in different materials. To conduct 3D ultrasound imaging, 2D ultrasound transducer arrays followed by multi-channel high-frequency data acquisition (DAQ) systems are frequently used. However, as the quantity and density of the transducer elements and also the DAQ channels increase, the acoustic imaging system becomes complex, bulky, expensive, and also power consuming. This situation is especially true for 3D imaging systems, where a 2D transducer array with hundreds or even thousands of elements could be involved. To address this issue, the objective of this research is to achieve new micromachined scanning devices to enable fast and versatile 2D ultrasound signal acquisition for 3D image reconstruction without involving complex physical transducer arrays and DAQ electronics. The new micromachined scanning devices studied in this research include 1) a water-immersible scanning mirror microsystem, 2) a micromechanical scanning transducer, and 3) a multi-layer linear transducer array. Especially, the water-immersible scanning mirror microsystem is capable of scanning focused ultrasound beam (from a single-element transducer) in two dimensions for 3D high-resolution acoustic microscopy. The micromechanical scanning transducer is capable of sending and receiving ultrasound signal from a single-element transducer to a 2D array of locations for 3D acoustic tomography. The multi-layer linear transducer array allows a unique electronic scanning scheme to simulate the functioning of a much larger 2D transducer array for 3D acoustic tomography. The design, fabrication and testing of the above three devices have been successfully accomplished and their applications in 3D acoustic microscopy and tomography have been demonstrated