414 research outputs found
N-variant Hardware Design
The emergence of lightweight embedded devices imposes stringent constraints on
the area and power of the circuits used to construct them. Meanwhile, many of
these embedded devices are used in applications that require diversity and flexibility
to make them secure and adaptable to the fluctuating workload or variable fabric.
While field programmable gate arrays (FPGAs) provide high flexibility, the use of
application specific integrated circuits (ASICs) to implement such devices is more
appealing because ASICs can currently provide an order of magnitude less area and
better performance in terms of power and speed. My proposed research introduces the
N-variant hardware design methodology that adds the sufficient flexibility needed by
such devices while preserving the performance and area advantages of using ASICs.
The N-variant hardware design embeds different variants of the design control
part on the same IC to provide diversity and flexibility. Because the control circuitry
usually represents a small fraction of the whole circuit, using multiple versions of the
control circuitry is expected to have a low overhead. The objective of my thesis is to
formulate a method that provides the following advantages: (i) ease of integration in
the current ASIC design flow, (ii) minimal impact on the performance and area of the
ASIC design, and (iii) providing a wide range of applications for hardware security
and tuning the performance of chips either statically (e.g., post-silicon optimization)
or dynamically (at runtime). This is achieved by adding diversity at two orthogonal
levels: (i) state space diversity, and (ii) scheduling diversity. State space diversity
expands the state space of the controller. Using state space diversity, we introduce
an authentication mechanism and the first active hardware metering schemes. On the
other hand, scheduling diversity is achieved by embedding different control schedules
in the same design. The scheduling diversity can be spatial, temporal, or a hybrid
of both methods. Spatial diversity is achieved by implementing multiple control
schedules that use various parts of the chip at different rates. Temporal diversity
provides variants of the controller that can operate at unequal speeds. A hybrid of
both spatial and temporal diversities can also be implemented. Scheduling diversity
is used to add the flexibility to tune the performance of the chip. An application
of the thermal management of the chip is demonstrated using scheduling diversity.
Experimental results show that the proposed method is easy to integrate in the current
ASIC flow, has a wide range of applications, and incurs low overhead
Fast algorithms for retiming large digital circuits
The increasing complexity of VLSI systems and shrinking time to market requirements demand good optimization tools capable of handling large circuits. Retiming is a powerful transformation that preserves functionality, and can be used to optimize sequential circuits for a wide range of objective functions by judiciously relocating the memory elements. Leiserson and Saxe, who introduced the concept, presented algorithms for period optimization (minperiod retiming) and area optimization (minarea retiming). The ASTRA algorithm proposed an alternative view of retiming using the equivalence between retiming and clock skew optimization;The first part of this thesis defines the relationship between the Leiserson-Saxe and the ASTRA approaches and utilizes it for efficient minarea retiming of large circuits. The new algorithm, Minaret, uses the same linear program formulation as the Leiserson-Saxe approach. The underlying philosophy of the ASTRA approach is incorporated to reduce the number of variables and constraints in this linear program. This allows minarea retiming of circuits with over 56,000 gates in under fifteen minutes;The movement of flip-flops in control logic changes the state encoding of finite state machines, requiring the preservation of initial (reset) states. In the next part of this work the problem of minimizing the number of flip-flops in control logic subject to a specified clock period and with the guarantee of an equivalent initial state, is formulated as a mixed integer linear program. Bounds on the retiming variables are used to guarantee an equivalent initial state in the retimed circuit. These bounds lead to a simple method for calculating an equivalent initial state for the retimed circuit;The transparent nature of level sensitive latches enables level-clocked circuits to operate faster and require less area. However, this transparency makes the operation of level-clocked circuits very complex, and optimization of level-clocked circuits is a difficult task. This thesis also presents efficient algorithms for retiming large level-clocked circuits. The relationship between retiming and clock skew optimization for level-clocked circuits is defined and utilized to develop efficient retiming algorithms for period and area optimization. Using these algorithms a circuit with 56,000 gates could be retimed for minimum period in under twenty seconds and for minimum area in under 1.5 hours
Advanced Algorithms for VLSI: Statistical Circuit Optimization and Cyclic Circuit Analysis
This work focuses on two emerging fields in VLSI. The first is use of statistical formulations to tackle one of the classical problems in VLSI design and analysis domains, namely gate sizing. The second is on analysis of nontraditional digital systems in the form of cyclic combinational circuits.
In the first part, a new approach for enhancing the process-variation tolerance of digital circuits is described. We extend recent advances in statistical timing analysis into an optimization framework. Our objective is to reduce the performance variance of a technology-mapped circuit where delays across elements are represented by random variables which capture the manufacturing variations. We introduce the notion of statistical critical paths, which account for both means and variances of performance variation. An optimization engine is used to size gates with a goal of reducing the timing variance along the statistical critical paths. Circuit optimization is carried out using a gain-based gate sizing algorithm that terminates when constraints are satisfied or no further improvements can be made. We show optimization results that demonstrate an average of 72% reduction in performance variation at the expense of average 20% increase in design area.
In the second part, we tackle the problem of analyzing cyclic circuits. Compiling high-level hardware languages can produce circuits containing combinational cycles that can never be sensitized. Such circuits do have well-defined functional behavior, but wreak havoc with most tools, which assume acyclic combinational logic. As such, some sort of cycle-removal step is usually necessary. We present an algorithm able to quickly and exactly characterize all combinational behavior of a cyclic circuit. It used a combination of explicit and implicit methods to compute input patterns that make the circuit behave combinationally. This can be used to restructure the circuit into an acyclic equivalent, report errors, or as an optimization aid. Experiments show our algorithm runs several orders of magnitude faster than existing ones on real-life cyclic circuits, making it useful in practice
The Second NASA Formal Methods Workshop 1992
The primary goal of the workshop was to bring together formal methods researchers and aerospace industry engineers to investigate new opportunities for applying formal methods to aerospace problems. The first part of the workshop was tutorial in nature. The second part of the workshop explored the potential of formal methods to address current aerospace design and verification problems. The third part of the workshop involved on-line demonstrations of state-of-the-art formal verification tools. Also, a detailed survey was filled in by the attendees; the results of the survey are compiled
Recommended from our members
Improving School Improvement
PREFACEIn opening this volume, you might be thinking:Is another book on school improvement really needed?Clearly our answer is yes. Our analyses of prevailing school improvement legislation, planning, and literature indicates fundamental deficiencies, especially with respect to enhancing equity of opportunity and closing the achievement gap.Here is what our work uniquely brings to policy and planning tables:(1) An expanded framework for school improvement – We highlight that moving from a two- to a three-component policy and practice framework is essential for closing the opportunity and achievement gaps. (That is, expanding from focusing primarily on instruction and management/government concerns by establishing a third primary component to improve how schools address barriers to learning and teaching.)(2) An emphasis on integrating a deep understanding of motivation – We underscore that concerns about engagement, management of behavior, school climate, equity of opportunity, and student outcomes require an up-to-date grasp of motivation and especially intrinsic motivation.(3) Clarification of the nature and scope of personalized teaching – We define personalization as the process of matching learner motivation and capabilities and stress that it is the learner's perception that determines whether the match is a good one.(4) A reframing of remediation and special education – We formulate these processes as personalized special assistance that is applied in and out of classrooms and practiced in a sequential and hierarchical manner.(5) A prototype for transforming student and learning supports – We provide a framework for a unified, comprehensive, and equitable system designed to address barriers to learning and teaching and re-engage disconnected students and families.(6) A reworking of the leadership structure for whole school improvement --We outline how the operational infrastructure can and must be realigned in keeping with a three component school improvement framework.(7) A systemic approach to enhancing school-community collaboration – We delineate a leadership role for schools in outreaching to communities in order to work on shared concerns through a formal collaborative operational infrastructure that enables weaving together resources to advance the work.(8) An expanded framework for school accountability – We reframe school accountability to ensure a balanced approach that accounts for a shift to a three component school improvement policy.(9) Guidance for substantive, scalable, and sustainable systemic changes –We frame mechanisms and discuss lessons learned related to facilitating fundamental systemic changes and replicating and sustaining them across a district.The frameworks and practices presented are based on our many years of work in schools and from efforts to enhance school-community collaboration. We incorporate insights from various theories and the large body of relevant research and from lessons learned and shared by many school leaders and staff who strive everyday to do their best for children.Our emphasis on new directions in no way is meant to demean current efforts. We know that the demands placed on those working in schools go well beyond what anyone should be asked to do. Given the current working conditions in many schools, our intent is to help make the hard work generate better results. To this end, we highlight new directions and systemic pathways for improving school outcomes.Some of what we propose is difficult to accomplish. Hopefully, the fact that there are schools, districts, and state agencies already trailblazing the way will engender a sense of hope and encouragement to those committed to innovation.It will be obvious that our work owes much to many. We are especially grateful to those who are pioneering major systemic changes across the country. These leaders and so many in the field have generously offered their insights and wisdom. And, of course, we are indebted to hundreds of scholars whose research and writing is a shared treasure. As always, we take this opportunity to thank Perry Nelson and the host of graduate and undergraduate students at UCLA who contribute so much to our work each day, and to the many young people and their families who continue to teach us all.Respectfully submitted for your consideration,Howard Adelman & Linda Taylo
Communication, Affect, & Learning in the Classroom
The purpose of the handbook was to synthesize the first three decades of research in instructional communication into a single volume that could help both researchers and instructors understand the value of communication in the instructional process.Preface1.Teaching As a Communication Process
The Instructional Communication Process
The Teacher
The Content
The Instructional Strategy
The Student
The Feedback/Evaluation
The Learning Environment/Instructional Context
Kibler’s Model of Instruction
The ADDIE Model of Instructional Design2.Communicating With Instructional Objectives
Why Some Teachers Resent Objectives
The Value of Objectives
What Objectives Should Communicate3.Instructional Communication Strategies
The Teacher As a Speaker
The Teacher As a Moderator
The Teacher As a Trainer
The Teacher As a Manager
The Teacher As a Coordinator & Innovator4.Communication, Affect, and Student Needs
Measuring Student Affect
Basic Academic Needs of Students
Traditional Interpersonal Need Models
Outcomes of Meeting Student Needs5.Learning Styles
What is Learning Style?
Dimensions of Learning Style and Their Assessment
Matching, Bridging, and Style-Flexing6.Classroom Anxieties and Fears
Communication Apprehension
Receiver Apprehension
Writing Apprehension
Fear of Teacher
Evaluation Apprehension
Classroom Anxiety
Probable Causes of Classroom Anxiety
Communication Strategies for Reducing Classroom Anxiety7.Communication And Student Self-Concept
Student Self-Concept: Some Definitions
Characteristics of the Self
Development of Student Self-Concept
Dimensions of Student Self-Concept
Self-Concept and Academic Achievement
Effects of Self-Concept on Achievement
Poker Chip Theory of Learning
Communication Strategies for Nurturing and Building Realistic Student Self-Concept8.Instructional Assessment:Feedback,Grading, and Affect
Defining the Assessment Process
Evaluative Feedback
Descriptive Feedback
Assessment and Affect
Competition and Cooperation in Learning Environments9.Traditional and Mastery Learning Systems
Traditional Education Systems
Mastery Learning
Modified Mastery Learning10.Student Misbehavior and Classroom Management
Why Students Misbehave
Categories of Student Behaviors
Students’ Effects on Affect in the Classroom
Communication, Affect, and Classroom Management
Communication Techniques for Increasing or Decreasing Student Behavior11.Teacher Misbehaviors and Communication
Why Teachers Misbehave
Common Teacher Misbehaviors
Implications for the Educational Systems12.Teacher Self-Concept and Communication
Dimensions of Teacher Self-Concept
Development of Teacher Self-Concept
Strategies for Increasing Teacher Self-Concept13.Increasing Classroom Affect Through
Teacher Communication Style
Communicator Style Concept
Types of Communicator Styles
Teacher Communication Style
Teacher Communicator Behaviors That Build Affect14.Teacher Temperament in the Classroom
Four Personality Types
Popular Sanguine
Perfect Melancholy
Powerful Choleric
Peaceful Phlegmatic
Personality Blends15.Teacher Communication: Performance and Burnout Teaching: A Multifaceted Job
Roles of an Instructional Manager
Teacher Burnout
Symptoms of Teacher Burnout
Causes of Teacher Burnout
Methods for Avoiding Burnout
Mentoring to Prevent BurnoutAppendix A To Mrs. Russell:
Without You This Never Would Have HappenedGlossaryInde
The Fifth NASA Symposium on VLSI Design
The fifth annual NASA Symposium on VLSI Design had 13 sessions including Radiation Effects, Architectures, Mixed Signal, Design Techniques, Fault Testing, Synthesis, Signal Processing, and other Featured Presentations. The symposium provides insights into developments in VLSI and digital systems which can be used to increase data systems performance. The presentations share insights into next generation advances that will serve as a basis for future VLSI design
Parallel and Distributed Computing
The 14 chapters presented in this book cover a wide variety of representative works ranging from hardware design to application development. Particularly, the topics that are addressed are programmable and reconfigurable devices and systems, dependability of GPUs (General Purpose Units), network topologies, cache coherence protocols, resource allocation, scheduling algorithms, peertopeer networks, largescale network simulation, and parallel routines and algorithms. In this way, the articles included in this book constitute an excellent reference for engineers and researchers who have particular interests in each of these topics in parallel and distributed computing
The Sixth Annual Workshop on Space Operations Applications and Research (SOAR 1992)
This document contains papers presented at the Space Operations, Applications, and Research Symposium (SOAR) hosted by the U.S. Air Force (USAF) on 4-6 Aug. 1992 and held at the JSC Gilruth Recreation Center. The symposium was cosponsored by the Air Force Material Command and by NASA/JSC. Key technical areas covered during the symposium were robotic and telepresence, automation and intelligent systems, human factors, life sciences, and space maintenance and servicing. The SOAR differed from most other conferences in that it was concerned with Government-sponsored research and development relevant to aerospace operations. The symposium's proceedings include papers covering various disciplines presented by experts from NASA, the USAF, universities, and industry
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