Distributed load balancing for parallel main memory hash join

Parallel joins have been widely studied during the past decade and a number of efficient algorithms were presented. While it is known that the performance of these algorithms may suffer greatly in the presence of skewed input data, the work on load balancing schemes for parallel join has been limited. The main contribution of this paper is the development and analysis of a new distributed data structure and an effective load balancing scheme for parallel main memory hash join on NUMA architecture. Multiprocessors based on this architecture are scalable in both size of main memory and number of processors, and provide very high memory bandwidth. The load balancing scheme is based on random probing to avoid the hot spot problems caused by probing sequentially. We have modeled this load balancing scheme both analytically and experimentally. The experiments were run on a BBN TC2000 multiprocessor system     

The NUMA with clusters of processors for parallel join

A number of hybrid systems have been proposed to combine the advantages of shared nothing and shared everything concepts for computing relational join operations. Most of these proposed systems, however, presented a few analytical results and have produced limited or no implementations on actual multiprocessors. In this paper, we present a parallel join algorithm with load-balancing for a hybrid system that combines both shared-nothing and shared-everything architectures. We derive an analytical model for the join algorithm on this architecture and validate it using both hardware/software simulations and actual experimentations. We study the performance of the join on the hybrid system for a wide range of system parameter values. We conclude that the hybrid system outperforms both shared-nothing and shared-everything architectures     

Calibration results on a new integrating instrument for measuring daily values of total solar radiation

Test results are reported for a newly develope instrument for accurately measuring daily solar radiation. The instrument consists of two components: the radiation sensor (a silicon-cell pyranometer that is mounted outdoors in the same way as the conventional Eppley or Kipp pyranometer), and the integrator (a conventional household style d-c ampere-hour meter). No electric power is needed to operate the instrument, which is easily portable, reasonably robust, and inexpensive.

Calibrations were done in Barbados (latitude 13° 12′ N) over an eight-month period, and consisted of intercomparison of a number of the new instruments among themselves, as well as calibration against conventional Kipp and conventional Eppley solar radiation measuring systems.

Test results led to the following conclusions:

1. 1-Scatter in the daily values of solar radiation as measured by the new instruments, due to the inherent characteristics of the new instruments themselves, was within ±2 percent.

2. 2-When compared to a carefully maintained reference (Kipp or Eppley) system, the scatter of the calibration data was within ±3 percent.

3. 3-Because of the difficulty of accurately integrating the solar-radiation record that is obtained with conventional (Kipp or Eppley) systems in the coastal tropics (where cumulus cloud is prevalent), scatter of the calibration data over many months was as high as ±10 percent, but more than half of this scatter was attributable to the reference system and not to the new instruments.

4. 4-Although developed mainly for use in the tropics, the new instrument is suitable for year-round use at latitudes up to 35 or 40 degrees, and for summer use at even greater latitudes.

5. 5-Being portable and inexpensive, and at the same time surprisingly accurate and robust, the new instrument seems well suited for measuring solar radiation in such situations as irrigation control, estimating evaporation from dams, horticultural and agricultural research, and for meteorological and climatological purposes.

     

XrML-RBLicensing approach adapted to the BPEL process of composite web services

Web service orchestration represents an open and standards-based approach for connecting web services together leading to higher level of business processes. Business Process Execution Language (BPEL) engines are designed to handle this orchestration. However, web service compositions into BPEL suffer from several non-functional requirements such as security. To address this problem, we propose in this paper a novel approach that is based on a harmony between the licensing concept offered by eXtensible rights Markup Language (XrML), aspect-oriented programming (AOP), and web service compositions in BPEL. Our proposed approach, based on XrML, offers the ability to associate security licenses with activities offered by the composite web services. It allows to automatically generate BPEL aspects depending on the developed licenses, to separate between crosscutting concerns of the composed web services, and provides an easy way to include and update the non-functional requirements (e.g., security) into a BPEL process. It offers also the ability to validate the licenses, at runtime and without affecting the business logic of this model. To evaluate our approach, we have developed an inventory control system (ICS) sample that is composed of several web services. Case study and performance analysis are presented to demonstrate its feasibility as well.     

Social behavior correlates of cortisol activity in child care: gender differences and time-of-day effects

The relations between social behavior and daily patterns of a stress-sensitive hormone production were examined in preschool children (N = 75) attending center-based child care. Three behavioral dimensions, shy/anxious/internalizing, angry/aggressive/externalizing, and social competence, were assessed by teacher report and classroom observation, and their relations with 2 measures of cortisol activity, median (or typical) levels and reactivity (quartile range score between second and third quartile values) were explored. Cortisol-behavior relations differed by gender: significant associations were found for boys but not for girls. Specifically, for boys externalizing behavior was positively associated with cortisol reactivity, while internalizing behavior was negatively associated with median cortisol. Time of day of cortisol measurement affected the results. Surprisingly, median cortisol levels rose from morning to afternoon, a pattern opposite to that of the typical circadian rhythm of cortisol. This rise in cortisol over the day was positively correlated with internalizing behavior for boys. The methodological and theoretical implications of these findings for the study of the development of hormone-behavior relations are discussed.