Center for space microelectronics technology

The 1992 Technical Report of the Jet Propulsion Laboratory Center for Space Microelectronics Technology summarizes the technical accomplishments, publications, presentations, and patents of the center during the past year. The report lists 187 publications, 253 presentations, and 111 new technology reports and patents in the areas of solid-state devices, photonics, advanced computing, and custom microcircuits

New architectural paradigms for multi-petabyte distributed storage systems

In the not too distant future, programs such as NASA's Earth Observing System, NSF/ARPA/NASA's Digital Libraries Initiative and Intelligence Community's (NSA, CIA, NRO, etc.) mass storage system upgrades will all require multi-petabyte (petabyte: 1015 bytes of bitfile data) (or larger) distributed storage solutions. None of these requirements, as currently defined, will meet their objectives utilizing either today's architectural paradigms or storage solutions. Radically new approaches will be required to not only store and manage veritable 'mountain ranges of data', but to make the cost of ownership affordable, much less practical in today's (and certainly the future's) austere budget environment! Within this paper we will explore new architectural paradigms and project systems performance benefits and dollars per petabyte of information stored. We will discuss essential 'top down' approaches to achieving an overall systems level performance capability sufficient to meet the challenges of these major programs

Execution replay and debugging

As most parallel and distributed programs are internally non-deterministic -- consecutive runs with the same input might result in a different program flow -- vanilla cyclic debugging techniques as such are useless. In order to use cyclic debugging tools, we need a tool that records information about an execution so that it can be replayed for debugging. Because recording information interferes with the execution, we must limit the amount of information and keep the processing of the information fast. This paper contains a survey of existing execution replay techniques and tools.Comment: In M. Ducasse (ed), proceedings of the Fourth International Workshop on Automated Debugging (AADebug 2000), August 2000, Munich. cs.SE/001003

Efficient layering for high speed communication: the MPI over Fast Messages (FM) experience

We describe our experience of designing, implementing, and evaluating two generations of high performance communication libraries, Fast Messages (FM) for Myrinet. In FM 1, we designed a simple interface and provided guarantees of reliable and in-order delivery, and flow control. While this was a significant improvement over previous systems, it was not enough. Layering MPI atop FM 1 showed that only about 35 % of the FM 1 bandwidth could be delivered to higher level communication APIs. Our second generation communication layer, FM 2, addresses the identified problems, providing gather-scatter, interlayer scheduling, receiver flow control, as well as some convenient API features which simplify programming. FM 2 can deliver 55–95 % to higher level APIs such as MPI. This is especially impressive as the absolute bandwidths delivered have increased over fourfold to 90 MB/s. We describe general issues encountered in matching two communication layers, and our solutions as embodied in FM 2

The Influence of Enterprise Online Information Behavior on Consumer Satisfaction

Based on findings from previous studies a model of the influence of enterprise online information behavior on consumer behaviors was formulated, analyzed, and developed using data collected by questionnaire from a sample of 479 consumers in the context of China. Enterprise behavior is represented by three constructs (information disclosure, interaction, and utilization) which influence consumer behaviors related to perceptions of pleasure, control, and attention and in turn consumer satisfaction. Many of the findings related to direct effects that have been reported in previous studies conducted in the context of western societies were confirmed. However, there were new findings related to significant direct, indirect, and total effects on consumer satisfaction due to information disclosure, interaction, and utilization. Apart from the theoretical contribution of the study, especially the analysis of indirect and total effects, there were practical implications. These are discussed with the objective of improving enterprise online behaviors with positive consequences for consumer behaviors and especially for improved consumer satisfaction. Importantly, the study addresses the limited number of previous studies conducted with Chinese consumers in online environments in China

A wildland fire model with data assimilation

A wildfire model is formulated based on balance equations for energy and fuel, where the fuel loss due to combustion corresponds to the fuel reaction rate. The resulting coupled partial differential equations have coefficients that can be approximated from prior measurements of wildfires. An ensemble Kalman filter technique with regularization is then used to assimilate temperatures measured at selected points into running wildfire simulations. The assimilation technique is able to modify the simulations to track the measurements correctly even if the simulations were started with an erroneous ignition location that is quite far away from the correct one.Comment: 35 pages, 12 figures; minor revision January 2008. Original version available from http://www-math.cudenver.edu/ccm/report

Corporate influence and the academic computer science discipline. [4: CMU]

Prosopographical work on the four major centers for computer research in the United States has now been conducted, resulting in big questions about the independence of, so called, computer science

Spatial and temporal-based query disambiguation for improving web search

Queries submitted to search engines are ambiguous in nature due to users’ irrelevant input which poses real challenges to web search engines both towards understanding a query and giving results. A lot of irrelevant and ambiguous information creates disappointment among users. Thus, this research proposes an ambiguity evolvement process followed by an integrated use of spatial and temporal features to alleviate the search results imprecision. To enhance the effectiveness of web information retrieval the study develops an enhanced Adaptive Disambiguation Approach for web search queries to overcome the problems caused by ambiguous queries. A query classification method was used to filter search results to overcome the imprecision. An algorithm was utilized for finding the similarity of the search results based on spatial and temporal features. Users’ selection based on web results facilitated recording of implicit feedback which was then utilized for web search improvement. Performance evaluation was conducted on data sets GISQC_DS, AMBIENT and MORESQUE comprising of ambiguous queries to certify the effectiveness of the proposed approach in comparison to a well-known temporal evaluation and two-box search methods. The implemented prototype is focused on ambiguous queries to be classified by spatial or temporal features. Spatial queries focus on targeting the location information whereas temporal queries target time in years. In conclusion, the study used search results in the context of Spatial Information Retrieval (S-IR) along with temporal information. Experiments results show that the use of spatial and temporal features in combination can significantly improve the performance in terms of precision (92%), accuracy (93%), recall (95%), and f-measure (93%). Moreover, the use of implicit feedback has a significant impact on the search results which has been demonstrated through experimental evaluation.SHAHID KAMA

Probing for Semantic Classes: Diagnosing the Meaning Content of Word Embeddings

Word embeddings typically represent differ- ent meanings of a word in a single conflated vector. Empirical analysis of embeddings of ambiguous words is currently limited by the small size of manually annotated resources and by the fact that word senses are treated as unrelated individual concepts. We present a large dataset based on manual Wikipedia an- notations and word senses, where word senses from different words are related by semantic classes. This is the basis for novel diagnos- tic tests for an embedding’s content: we probe word embeddings for semantic classes and an- alyze the embedding space by classifying em- beddings into semantic classes. Our main find- ings are: (i) Information about a sense is gen- erally represented well in a single-vector em- bedding – if the sense is frequent. (ii) A clas- sifier can accurately predict whether a word is single-sense or multi-sense, based only on its embedding. (iii) Although rare senses are not well represented in single-vector embed- dings, this does not have negative impact on an NLP application whose performance depends on frequent senses