251 research outputs found
Exploring the Mysteries of System-Level Test
System-level test, or SLT, is an increasingly important process step in
today's integrated circuit testing flows. Broadly speaking, SLT aims at
executing functional workloads in operational modes. In this paper, we
consolidate available knowledge about what SLT is precisely and why it is used
despite its considerable costs and complexities. We discuss the types or
failures covered by SLT, and outline approaches to quality assessment, test
generation and root-cause diagnosis in the context of SLT. Observing that the
theoretical understanding for all these questions has not yet reached the level
of maturity of the more conventional structural and functional test methods, we
outline new and promising directions for methodical developments leveraging on
recent findings from software engineering.Comment: 7 pages, 2 figure
Innovative Techniques for Testing and Diagnosing SoCs
We rely upon the continued functioning of many electronic devices for our everyday welfare,
usually embedding integrated circuits that are becoming even cheaper and smaller
with improved features. Nowadays, microelectronics can integrate a working computer
with CPU, memories, and even GPUs on a single die, namely System-On-Chip (SoC).
SoCs are also employed on automotive safety-critical applications, but need to be tested
thoroughly to comply with reliability standards, in particular the ISO26262 functional
safety for road vehicles.
The goal of this PhD. thesis is to improve SoC reliability by proposing innovative
techniques for testing and diagnosing its internal modules: CPUs, memories, peripherals,
and GPUs. The proposed approaches in the sequence appearing in this thesis are described
as follows:
1. Embedded Memory Diagnosis: Memories are dense and complex circuits which
are susceptible to design and manufacturing errors. Hence, it is important to understand
the fault occurrence in the memory array. In practice, the logical and physical
array representation differs due to an optimized design which adds enhancements to
the device, namely scrambling. This part proposes an accurate memory diagnosis
by showing the efforts of a software tool able to analyze test results, unscramble
the memory array, map failing syndromes to cell locations, elaborate cumulative
analysis, and elaborate a final fault model hypothesis. Several SRAM memory failing
syndromes were analyzed as case studies gathered on an industrial automotive
32-bit SoC developed by STMicroelectronics. The tool displayed defects virtually,
and results were confirmed by real photos taken from a microscope.
2. Functional Test Pattern Generation: The key for a successful test is the pattern applied
to the device. They can be structural or functional; the former usually benefits
from embedded test modules targeting manufacturing errors and is only effective
before shipping the component to the client. The latter, on the other hand, can be
applied during mission minimally impacting on performance but is penalized due
to high generation time. However, functional test patterns may benefit for having
different goals in functional mission mode. Part III of this PhD thesis proposes
three different functional test pattern generation methods for CPU cores embedded
in SoCs, targeting different test purposes, described as follows:
a. Functional Stress Patterns: Are suitable for optimizing functional stress during
I
Operational-life Tests and Burn-in Screening for an optimal device reliability
characterization
b. Functional Power Hungry Patterns: Are suitable for determining functional
peak power for strictly limiting the power of structural patterns during manufacturing
tests, thus reducing premature device over-kill while delivering high test
coverage
c. Software-Based Self-Test Patterns: Combines the potentiality of structural patterns
with functional ones, allowing its execution periodically during mission.
In addition, an external hardware communicating with a devised SBST was proposed.
It helps increasing in 3% the fault coverage by testing critical Hardly
Functionally Testable Faults not covered by conventional SBST patterns.
An automatic functional test pattern generation exploiting an evolutionary algorithm
maximizing metrics related to stress, power, and fault coverage was employed
in the above-mentioned approaches to quickly generate the desired patterns. The
approaches were evaluated on two industrial cases developed by STMicroelectronics;
8051-based and a 32-bit Power Architecture SoCs. Results show that generation
time was reduced upto 75% in comparison to older methodologies while
increasing significantly the desired metrics.
3. Fault Injection in GPGPU: Fault injection mechanisms in semiconductor devices
are suitable for generating structural patterns, testing and activating mitigation techniques,
and validating robust hardware and software applications. GPGPUs are
known for fast parallel computation used in high performance computing and advanced
driver assistance where reliability is the key point. Moreover, GPGPU manufacturers
do not provide design description code due to content secrecy. Therefore,
commercial fault injectors using the GPGPU model is unfeasible, making radiation
tests the only resource available, but are costly. In the last part of this thesis, we
propose a software implemented fault injector able to inject bit-flip in memory elements
of a real GPGPU. It exploits a software debugger tool and combines the
C-CUDA grammar to wisely determine fault spots and apply bit-flip operations in
program variables. The goal is to validate robust parallel algorithms by studying
fault propagation or activating redundancy mechanisms they possibly embed. The
effectiveness of the tool was evaluated on two robust applications: redundant parallel
matrix multiplication and floating point Fast Fourier Transform
Post-Silicon General Bus Function Model Modelling Approach Using C Code For Test Scheme Reuse And Sharing
Short product life cycle of a semiconductor IC is crucial for a company to gain better market share. But current validation process has become one of the bottleneck in semiconductor IC development process, where enhancement in this area can reduce the product lead time to market. There is a gap between pre- and post-silicon where both area is doing similar things but in different environment. A way to bridge the gap is by using the same test scheme which is applicable for both environment. This paper discuss and come out with an approach on how to model post-silicon BFM using high level programming language (C code) that is capable of content sharing and reuse between both pre- and post-silicon validation. Two methods to model post-silicon BFM are being approached and the more suitable one is being selected. The comparison is done is aspect of meeting strict timing requirement in sending signal. A prototype model of the selected model, which is second model is developed and tested in post-silicon validation environment to prove validity of the design. Test content in C code is created and synthesize into FPGA, act as stimulus generator for validation. The BFM device bit-accuracy behavior of the modelled Audio bus protocol is checked with waveform and signal trace. With this working model for developing BFM, pre- and post-silicon validation can share the same test scheme, saving efforts and time of developing test devices
Viking '75 spacecraft design and test summary. Volume 3: Engineering test summary
The engineering test program for the lander and the orbiter are presented. The engineering program was developed to achieve confidence that the design was adequate to survive the expected mission environments and to accomplish the mission objective
A Methodology for Implementing RF BiSTs in Production Testing to Replace RF Conventional Tests
Production testing of Radio Frequency (RF) devices is challenging due to the complex nature of the tests that have to be performed to verify functionality. In this dissertation a methodology to replace the complex and expensive RF functional tests with defect-oriented Built-in Self Tests (BiSTs) is detailed. If a design has sufficient margin to RF specifications then RF tests can be replaced with structural tests using a new data analysis technique called quadrant analysis, which is presented. Data from the analysis of over one million production units of said System on Chip (SoC) is presented along with the results of the analysis. The BiST techniques that have been used are discussed and a Texas Instruments 65 nm RF SoC with a Bluetooth and a FM core was used as a case study. The defect models that were used to develop the BiSTs are discussed as well. The scenario in which a design does not have sufficient margin to specification is also discussed. The data analysis method required in such a case is a regression analysis and the data from such an analysis is shown. The results prove that it is possible to replace expensive RF conventional tests with structural tests and that modern RFCMOS process technology and advances in design like the Digital Radio Processor (DRPTM) technology enable this. The Defective Parts Per Million (DPPM) impact of making this replacement is 27 units and is acceptable for RFCMOS high volume products. Finally, data showing test cost reduction of about 38% that resulted from the elimination of RF conventional tests is presented
Nutrition and biomarkers in psychiatry : research on micronutrient deficiencies in schizophrenia, the role of the intestine in the hyperserotonemia of autism, and a method for non-hypothesis driven discovery of biomarkers in urine
This thesis describes the study of markers of nutrition and intestinal motility in mental disorders with a focus on schizophrenia and autism, and the development, evaluation and application of a biomarker discovery method for urine. The aim of the thesis is to investigate the role of long-chain polyunsaturated fatty acids (LCPUFA), B-vitamins and platelet (PLT) serotonin (5-HT) in schizophrenia and autism. The thesis proposes also that biomarker research in psychiatric disease is of great relevance and describes a biomarker discovery method in urine using a non-hypothesis driven ‘-omics’-like approach. The thesis ends by summarizing its contents and putting biomarker research in psychiatric disease and its implications in a broader perspective.
In the Introduction the complex etiology and potential role of non-hypothesis driven biomarker research in psychiatric disease is reviewed, with an accent on schizophrenia and autism. The enormous economic and psychosocial global burden of mental disorders is described as well as their epidemiology, clinical presentation and classification/diagnosis. Hypothesized etiological factors are discussed to create a framework in which biomarkers and the research thereof can be positioned. Furthermore, advances in the field of biomarker research in psychiatry are discussed in the context of epigenetics, proteomics and metabolomics.
The first part (Part I) of this thesis describes a study of LCPUFA and B-vitamins in schizophrenia, of PLT 5-HT and intestinal permeability in autism, and of the value of PLT 5-HT as marker of intestinal motility in newborns. The chapters, in which these studies are described, are preceded by a review (Chapter 1), which gives an overview of the role of LCPUFA and folate in the etiology and severity of psychiatric diseases such as depression, bipolar disorders, schizophrenia and autism. Pregnancy complications and folate-substrated carbon-1 metabolism are considered and their possible epigenetic effect on the etiology of mental disorders is described. Other nutritional factors, such as LCPUFA, that are important for brain development, physico-chemical properties of membranes, signal transduction and DNA-transcription, and that have been used in supplementation trials, are suggested to be important factors in the origin and severity of schizophrenia. In Chapter 2 we describe the results from a study concerning the essential fatty acid (EFA) and functional B-vitamin status in patients with schizophrenia. Aberrant EFA-status and increased homocysteine (Hcy; a marker of functional B-vitamin deficiency), have been reported before in subgroups of patients with schizophrenia. We describe the characteristics of large subgroups with marginal to severe deficiencies of LCPUFA and B-vitamins, notably folate and vitamin B12. Deficiencies proved easily correctable in the most severely deficient patients upon supplementation with ω3 fatty acids and B-vitamins. Chapter 3 attempts to integrate and link previously reported findings of increased intestinal permeability and increased PLT 5-HT levels in subgroups of children with pervasive developmental disorders (PDD). Platelet 5-HT and intestinal permeability were assessed in children with PDD in Curaçao. Differential urinary excretion of inert sugars after ingestion of a sugar solution was used as marker of intestinal permeability. In Chapter 4 we examined the potential of PLT 5-HT as marker of intestinal motility. For this we studied whole blood and PLT 5-HT in mothers (normal motility) and their newborns (developing intestinal motility) at birth. The course of PLT 5-HT in relation to changes in feeding mode (i.e. parenteral/enteral) was investigated in a small group of preterm born infants to see whether PLT 5-HT was responsive to changes in intestinal motility. Chapters 2, 3 and 4 describe hypothesis-driven research in mental disorders. However, the advance of knowledge about mental disorders is slow and it is likely to benefit from complementation by information that is generated through non-hypothesis driven research with state-of-the art techniques that profile proteins (i.e. proteomics) and metabolites (i.e. metabolomics). These ‘-omics’ techniques are likely to deliver a multitude of candidate diagnostic and prognostic markers as well as therapeutic targets, compared to hypothesis driven research.
Part II is thus devoted to the development, evaluation and application of such a non-hypothesis driven method. In Chapter 5 we describe the comparative analysis of low molecular weight urinary components using LC-MS and subsequent multivariate statistical analysis of the processed LC-MS data. This chapter deals with the development, evaluation and preliminary application of the method to proteinuria in humans. The potential and pitfalls of the method are contemplated upon. Chapter 6 describes an advanced proof-of-principle of the method through the comparison of urinary profiles from pregnant and non-pregnant females using the improved methodology described in Chapter 5. The methodology is significantly optimized with respect to data processing and multivariate statistical analysis. More focus is put on the selection of discriminatory peaks.
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Éénderde van de patiënten met schizofrenie blijkt matige tot ernstige tekorten aan bepaalde B-vitaminen en ω3- en ω6-vetzuren te hebben. Deze tekorten zijn eenvoudig op te heffen met voedingsupplementen (o.a. foliumzuur en visolie). Een lage status van deze micronutriënten speelt waarschijnlijk een rol in het ontstaan en de ernst van diverse psychiatrische ziekten en het ontstaan van hart- en vaatziekten. De behandelende artsen vermoedden het bestaan van deze tekorten niet.
Ongeveer een kwart van de patiënten met autisme heeft een verhoogd serotoninegehalte in bloedplaatjes (hyperserotonemie: “biomarker”). Serotonine is een neurotransmitter in onze hersenen en darmen. Autisten zouden ook vaker maagdarmstoornissen hebben. We vonden geen relatie tussen hyperserotonemie (26%) en de darmdoorlaatbaarheid (in 0% verhoogd) in kinderen met autisme. Het idee dat een verhoogde darmmotiliteit hyperserotonemie veroorzaakt, werd ondersteund door een twee maal hoger bloedplaatjesserotonine van moeders (actieve darm) t.o.v. hun pasgeboren baby’s (inactieve darm). Tevens bleek starten en staken van enterale voeding in pasgeborenen gecorreleerd aan respectievelijk stijgingen en dalingen van hun bloedplaatjesserotonine. Meer onderzoek naar het maagdarmstelsel (onze “second brain”) bij autisme is gewenst.
Niet-hypothesegedreven onderzoek als aanvulling op het veelal hypothesegedreven onderzoek kan helpen bij het vinden van diagnostische en therapeutische biomarkers voor psychiatrische stoornissen. De hiertoe opgezette methode onderzoekt urinemonsters met vloeistofchromatografie-massaspectrometrie, waarna de 3D-data multivariaat geanalyseerd worden om biomarkers te ontdekken. Experimenten met urinemonsters van patiënten met eiwit in hun urine (vanwege een nierziekte) en controles, en van zwangere en niet-zwangere vrouwen, lieten duidelijke groepsverschillen zien (“proof-of-principle”). Dit geeft hoop dat de ontwikkelde methode in de toekomst gebruikt kan worden voor het opsporen van biomarkers bij psychiatrische stoornissen en andere ziektes.
Technological and Institutional Innovations for Marginalized Smallholders in Agricultural Development
Agriculture; Agricultural Economics; Geography, general; Innovation/Technology Managemen
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