Maximum Hit Research Articles

Evaluating baseball bat performance

Selected methodologies currently used to assess baseball bat performance were evaluated through a series of finite element simulations. Results of the comparison show that current test methods contradict one another and do not describe the performance advantage of modern hollow bats over solid wood bats. The discrepancy was related to the way performance was quantified and the way the bat was tested. Performance metrics that do not consider a bat’s mass moment of inertia (MOI) were observed to underestimate the hitting performance of light weight bats. A bat’s centre of percussion was observed to be an unreliable indicator of its sweet spot (i.e. impact location providing the maximum hit ball speed). Bat performance was found to be sensitive to the relative impact speed between the bat and ball. From these observations three recommendations concerning bat performance were made: (1) performance should be measured at relative speeds between the bat and ball that are representative of play conditions; (2) the ball should impact the bat at its experimentally determined sweet spot; and (3) performance should be quantified from ball and bat speeds before and after impact. Using current test methods, an aluminium bat had a 0.9% higher performance over wood (maximum), while using the proposed recommendations the difference was 3.8% (average). The variation in the relative performance over three test conditions reduced from a 4% using current test methods to a 0.3% when the above recommendations were followed.

Implementation of the ASDBLR straw tube readout ASIC in DMILL technology

The ASDBLR application-specific integrated circuit (ASIC) provides eight channels of low-noise low-power high-rate on-detector readout suitable for the ATLAS transition radiation tracker (TRT) at the large hadron collider. The TRT's unprecedented wire chamber readout requirements of a maximum hit rate per wire of 20 MHz and double-pulse resolution of /spl sim/25 ns with position resolution of better than 150 /spl mu/m in a high radiation environment have been addressed in the design of the ASDBLR. A carefully tuned ion tail cancellation stage followed by an output sensing baseline restorer implemented in differential structures provides robust signal-processing combination compatible with the realities of ASIC design. Two comparators track the output of the signal-processing stage to provide tracking information from charged particles and evidence of higher energy transition radiation photons; their outputs are summed as current steps to form a differential ternary output. The ten-year total dose requirement for neutrons of 10/sup 14/ n/cm/sup 2/ and 1.5 MRad of ionizing radiation led to the implementation of this design in the radiation hardened DMILL process.

Modeling and simulation of a readout architecture for pixel detectors

This paper analyzes in detail some theoretical aspects in the modeling of a proposed readout architecture for pixel detectors. The readout architecture is designed for a chip containing about 3000 pixels of 50 /spl mu/m/spl times/400 /spl mu/m. The main objective is to get the maximum pixel hit readout with the minimum probability of hit loss. The readout architecture is modeled as a Markov stochastic process. The pixel front-end and readout are simulated and tested with Monte Carlo data. The simulations allow to optimize the communication channel bandwidths and local buffering. The probability of system overflow of the simulated system is confronted with the one obtained by modeling.

Studies on ageing effects and rate dependence of Thin Gap Chambers

We studied ageing effects of Thin Gap Chambers (TGC). The gas mixture was 55% of CO2 and 45% of n-pentane. The TGCs were irradiated with β-rays of a 90Sr source. The maximum hit rate per wire was 41–84kHz/cm. The gas flow rate was equivalent to replacing 0.3–2.6 of the TGC volume per minute. We observed neither significant deterioration on pulse height nor time jitter up to an accumulated charge of 1C/cm. We also performed a beam test to study the TGC performance under a high radiation environment. The maximum background rate of approximately 3.8MHz/cm2 was achieved using a 90Sr source. The pulse height did not change significantly up to background rates of 100kHz/cm2.

A 2D smart pixel detector for time-resolved crystallography

A smart pixel detector is being developed for time-resolved crystallography for biological and material science applications. Using the pixel detector presented here, the Laue method will enable the study of the evolution of structural changes that occur within a protein as a function of time. The x-ray pixellated detector is assembled to the integrated circuit through a bump bonding process. Within a pixel size of 150×150 mm2, a low-noise preamplifier-shaper, a discriminator, a 3-bit counter and the readout logic are integrated. The readout, based on the column architecture principle, will accept hit rates above 5×108/cm2/s with a maximum hit rate per pixel of 1 MHz. This detector will allow time-resolved Laue crystallography to be performed in a frameless operation mode, without dead time. Target specifications, architecture, and preliminary results on a 8×8 prototype are presented.

A 2D smart pixel detector for time resolved protein crystallography

A smart pixel detector is being developed for Time Resolved Crystallography for biological and material science applications. Using the Pixel Detector presented here, the Laue method will enable the study of the evolution of structural changes that occur within the protein as a function of time. The X-ray pixellated detector is assembled to the integrated circuit through a bump bonding process. Within a pixel size of 150/spl times/150 /spl mu/m/sup 2/, a low noise preamplifier-shaper, a discriminator, a 3 bit counter and the readout logic are integrated. The read out, based on the Column Architecture principle, will accept hit rates above 5/spl times/10/sup 8//cm/sup 2//s with a maximum hit rate per pixel of 1 MHz. This detector will allow time resolved Laue crystallography to be performed in a frameless operation mode, without dead time. Target specifications, architecture and preliminary results on the 8/spl times/8 front-end prototype and the column readout are presented.

Asymptotic performance of a buffer model in a data sharing environment

The performance of a transaction processing system is very sensitive to the buffer hit probability. In a data sharing environment where multiple computing nodes are coupled together with direct access to shared data on disks, buffer coherency needs to be maintained such that if a data granule is updated by a node, the old copies of this granule present in the buffer of other nodes must be invalidated. The buffer invalidation phenomenon reduces the buffer hit probability in a multi-node environment. After the buffer reaches a certain size, the buffer hit probability will remain constant regardless of further increase in buffer size due to the buffer invalidation effect. This puts an upper limit on the achievable buffer hit probability. Thus the selection of appropriate buffer size is one of the critical issues in a data sharing environment. In this paper, we develop an asymptotic analysis of the Markov model for a buffer in the data sharing environment. Important relations between buffer size, number of nodes, write-probability and the size of the database to the buffer hit probability had been found in all range of system parameters. A simple expression is obtained for the maximum achievable buffer hit probability and also for the maximum usable buffer size. Various properties of the maximum achievable buffer hit probability and usable buffer size are derived for a skewed access workload. The accuracy of the asymptotic method is validated by numerous case studies.

２項事象系列の出現確率判断における確率認知

The fallacious probability judgment of binary event sequence (Bernoulli sequence) was studied in terms of probability cognition. The categorizational fallacy hypothesis (Kasai, 1982) asserts that people tend to respond with a categorical probability (the probability of occurrence of the category to which a given instance belongs) even when they are asked to answer the individual probability of instance. In Exp. 1, 46 undergraduates were instructed to make the paired comparison of probability among 15 binary sequences of length 6. Their modal judgments were compared with the theoretical predictions based on the ideal probability distributions and also with the predictions from the subjective distributions which were generated by 24 undergraduates in Exp. 2. The results confirmed the predictions, particularly those based on the subjective distributions (maximum hit rate 82.9%). Based on these results it was concluded that the subjects judged the likelihood of each sequence in terms of categorical probability rather than the required individual probability, and it was suggested that the fallacious judgment is derived from the cognitive process of abstracting and symbolizing.

Coding strategies in language

The problem of selecting a code to transmit four messages over the binary symmetric channel is studied in relation to two types of channel noise (“substitution≓ error and “deletion≓ error) and to two types of decoding strategy (maximum hit and minimum error). It is shown that mean Hamming distance is a good general guide to coding efficiency, except in the case of a minimum error strategy with a deletion error channel, where coding efficiency is critically dependent on noise level. An experiment in which subjects selected codes in an artificial language suggests that the process of recall from memory is similar to the process of transmitting over a deletion error channel with a minimum error strategy. A similar interpretation can be placed on the analysis of consonant systems in English, French, German and Welsh, where the sets of consonants of a given class in a given environment are considered as codes whose alphabet is the phonological distinctive feature system of Halle (1958)