Hewlett-Packard

About: Hewlett-Packard is a company organization based out in Palo Alto, California, United States. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 34663 authors who have published 59808 publications receiving 1467218 citations. The organization is also known as: Hewlett Packard & Hewlett-Packard Company.

OLTP through the looking glass, and what we found there

Abstract: Online Transaction Processing (OLTP) databases include a suite of features - disk-resident B-trees and heap files, locking-based concurrency control, support for multi-threading - that were optimized for computer technology of the late 1970's Advances in modern processors, memories, and networks mean that today's computers are vastly different from those of 30 years ago, such that many OLTP databases will now fit in main memory, and most OLTP transactions can be processed in milliseconds or less Yet database architecture has changed littleBased on this observation, we look at some interesting variants of conventional database systems that one might build that exploit recent hardware trends, and speculate on their performance through a detailed instruction-level breakdown of the major components involved in a transaction processing database system (Shore) running a subset of TPC-C Rather than simply profiling Shore, we progressively modified it so that after every feature removal or optimization, we had a (faster) working system that fully ran our workload Overall, we identify overheads and optimizations that explain a total difference of about a factor of 20x in raw performance We also show that there is no single "high pole in the tent" in modern (memory resident) database systems, but that substantial time is spent in logging, latching, locking, B-tree, and buffer management operations

Efficient and practical fair exchange protocols with off-line TTP

Abstract: We present protocols for fair exchange of electronic data (digital signatures, payment and confidential data) between two parties A and B. Novel properties of the proposed protocols include: 1) offline trusted third party (TTP), i.e., TTP does not take part in the exchange unless one of the parties behaves improperly; 2) only three message exchanges are required in the normal situation; 3) true fair exchange, i.e., either A and B obtain each other's data or no party receives anything useful; no loss can be incurred to a party no matter how maliciously the other party behaves during the exchange. This last property is in contrast to previously proposed protocols with offline TTP ([1] and [21]), where a misbehaving party may get another party's data while refusing to send his document to the other party, and the TTP can provide affidavits attesting to what happened during the exchange. To our knowledge, the protocols presented here are the first exchange protocols which use offline TTP and at the same time guarantee true fair exchange of digital messages. We introduce a novel cryptographic primitive, called the Certificate of Encrypted Message Being a Signature (CEMBS), as the basic building block of the fair exchange protocols. It is used to prove that an encrypted message is a certain party's signature on a public file, without revealing the signature. We also give two examples to show in detail how the certificate can be constructed.

Using a model of social dynamics to predict popularity of news

Abstract: Popularity of content in social media is unequally distributed, with some items receiving a disproportionate share of attention from users. Predicting which newly-submitted items will become popular is critically important for both companies that host social media sites and their users. Accurate and timely prediction would enable the companies to maximize revenue through differential pricing for access to content or ad placement. Prediction would also give consumers an important tool for filtering the ever-growing amount of content. Predicting popularity of content in social media, however, is challenging due to the complex interactions among content quality, how the social media site chooses to highlight content, and influence among users. While these factors make it difficult to predict popularity a priori, we show that stochastic models of user behavior on these sites allows predicting popularity based on early user reactions to new content. By incorporating aspects of the web site design, such models improve on predictions based on simply extrapolating from the early votes. We validate this claim on the social news portal Digg using a previously-developed model of social voting based on the Digg user interface.

Phased array acoustic systems with intra-group processors

Abstract: The disclosed ultrasound imaging apparatus and method use a transducer array with a very large number of transducer elements or a transducer array with many more transducer elements than beamformer channels. The imaging apparatus includes a transmit array including a multiplicity of transducer elements allocated into several transmit sub-arrays, and a receive array including a multiplicity of transducer elements allocated into several receive sub-arrays. The apparatus also includes several intra-group transmit processors, connected to the transmit sub-arrays, constructed and arranged to generate a transmit acoustic beam directed into a region of interest, and several intra-group receive processors connected to the receive sub-arrays. Each intra-group receive processor is arranged to receive, from the transducer elements of the connected sub-array, transducer signals in response to echoes from the transmit acoustic beam. Each intra-group receive processor includes delay and summing elements constructed to delay and sum the received transducer signals. The apparatus also includes a receive beamformer including several processing channels connected to the intra-group receive processors, wherein each processing channel includes a beamformer delay constructed and arranged to synthesize receive beams from the echos by delaying signals received from the intra-group receive processor, and a beamformer summer (a summing junction) constructed and arranged to receive and sum signals from the processing channels. An image generator is constructed and arranged to form an image of the region of interest based on signals received from the receive beamformer. The apparatus is practical in size, cost and complexity and is sufficiently fast to provide two-dimensional or three-dimensional images of moving body organs.