The nonsqueaky wheel

This paper presents a new approach, termed performance-based maintenance, can utilize past and ongoing equipment maintenance records to prioritize electrical distribution equipment with greater detail. The proposed scheme provides cost savings and useful in identifying equipment that can have a lesser level of future maintenance, or extended maintenance cycles. The integration of multiple inputs is required to minimize the risks associated with improper equipment prioritization. The savings can be redirected to areas such as predictive diagnostics, which can provide for greater improvements in reliability while also reducing the over all spend on maintenance.     

居民区雷电保护系统的试验:火箭触发雷电和电流冲击发生器试验数据的比较

We present a comparison of data obtained during testing of lightning protective system of a residential structure in rocket-triggered lightning experiment at the International Center for Lightning Research and Testing(ICLRT)at Camp Blanding,Florida,and current surge generator experiment at Rzeszow University of Technology in Poland.Three different configurations of LPS were tested in Poland with the dc grounding resistances of the entire system 4.09 Ω(LPS 1a),1.65 Ω(LPS 1b),and 2.88 Ω(LPS 2).For LPS 1a with three ground rods the value of the peak current entering the electrical circuit neutral was about 56% of the injected current peak,and for LPS 1b with two additional ground rods and two 5 m long buried horizontal conductors it was about 16%.For LPS 2 with five ground rods interconnected by a buried loop conductor this ratio was 21%.The current waveshapes in the ground rods differed from the injected current waveshapes and the current waveshapes in other parts of the test system,especially,for poorer-grounding LPS 1a.The surge-generator results are consistent with those of triggered-lightning experiments at Camp Blanding,Florida(DeCarlo et al.,2008 [2]).     

Convex and Semi-Nonnegative Matrix Factorizations

We present several new variations on the theme of nonnegative matrix factorization (NMF). Considering factorizations of the form X=FG^T, we focus on algorithms in which G is restricted to containing nonnegative entries, but allowing the data matrix X to have mixed signs, thus extending the applicable range of NMF methods. We also consider algorithms in which the basis vectors of F are constrained to be convex combinations of the data points. This is used for a kernel extension of NMF. We provide algorithms for computing these new factorizations and we provide supporting theoretical analysis. We also analyze the relationships between our algorithms and clustering algorithms, and consider the implications for sparseness of solutions. Finally, we present experimental results that explore the properties of these new methods.     

Social influences related to college students’ use of Macintosh computers on an all-PC campus

In the present qualitative research study, 35 Mac users were interviewed in a university campus that exclusively supports PC machines. We particularly explored the Mac-users’ social influences, saving technological and other influences for future reports. Results showed Mac users to possess significant connections with other Mac users on the university campus. The Mac users in our study indicated that positive, past exposure, including Apple’s advertising of Macs, had sharp influences on their decisions to become and remain Mac users.     

Calculating fragment impact velocity from penetration data

Depth of penetration experiments were conducted with fragment simulating projectiles launched into Celotex^® in order to develop an equation for the strike velocity as a function of the FSP mass and the depth of penetration into Celotex^® recovery media. A powder gun launched FSPs, designed in accordance with STANAG-2920 [NATO STANAG-2920 Ballistic Test Method for Personal Armour Materials and Combat Clothing, 2nd ed., 1999.] weighing between 0.13 g and 53.78 g at striking velocities between 198 m/s and 1524 m/s. A multiple linear regression analysis was used to determine an empirical relationship for the strike velocity to the impact parameters of depth of penetration, fragment mass, and mean presented area. Sabot launched natural fragments weighing between 2.8 g and 15.8 g at striking velocities between 532 m/s and 1084 m/s were used to validate the equation.     

Speciation and distribution of alkali,alkali earth metals and major ash forming elements during gasification of fuel cane bagasse

Gasification of fuel cane bagasse, the waste residue from fuel cane, a hybrid of wild and commercial clones of sugar cane, was carried out in a novel 50 kWe air-blown autothermal downdraft gasifier. The speciation and distribution of alkali, alkali earth metals and major ash forming elements during gasification were investigated to evaluate the extent of volatilisation of these elements into the syngas and to determine the likely impact on syngas fuelled solid oxide fuel cell systems. Also assessed was the potential for defluidisation of the fuel bed due to agglomerate and deposit formation. Chemical fractionation studies showed that 30% of the potassium was captured by aluminosilicates and was retained in the ash, thereby reducing the alkali loading in the syngas and that more than 50% of the alkali earth metals were released to the syngas. In contrast, although the major ash forming elements were transformed from acid insoluble to acid soluble forms during gasification they remained hard bound in the ash and less than 30% of each one was released into the gas phase. The composition of clinkers and agglomerates produced during gasification was investigated by SEM-EDX and XRD which confirmed the presence of the eutectic systems KAlSi₂O₆–SiO₂, KAlSi₂O₆–CaMgSi₂O₆–SiO₂ and CaMgSi₂O₆–NaAlSi₃O₈. A preliminary model of the distribution behaviour during gasification of the ash forming elements has been developed.     

Large-Scale Tracing of Ground Water with Sulfur Hexafluoride

Sulfur hexafluoride (SF6) was injected into a 9 km reach of the Santa Ana River in Orange County, CA, over a period of two weeks. The entire flow of this river, which averaged 2.8 m3 s?1, percolated into the ground in the field area. The tracer was monitored at wells near the river to determine subsurface flow patterns and flow times with an accuracy much greater than could be achieved using numerical simulations of ground-water flow. During the experiment, SF6 effectively tagged 3.7 × 106 m3 of water. The tracer plume was mapped in the subsurface for 18 months and indicates that linear ground-water velocities averaged about 2 km year?1. The tracer reached two wells adjacent to the river (about 200 m away) within three weeks, giving evidence that SF6 was not retarded significantly relative to the ground-water flow. This is in agreement with previous laboratory experiments.     

Effects of peer support and therapist contact on long-term weight loss.

This study evaluated the effectiveness of two posttreatment programs designed to enhance the maintenance of weight loss. Eighty-five obese clients were randomly assigned to either (a) behavior therapy plus a peer-support maintenance program, (b) behavior therapy plus a therapist-contact maintenance program, or (c) behavior therapy only. At a 7-month follow-up session, the therapist-contact program resulted in significantly greater maintenance of weight loss compared with the peer support and behavior therapy only conditions. However, by the time of an 18-month follow-up assessment, overall relapse rates were equivalent across conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)