Performance evaluation of a.c. and d.c. direct coupled photovoltaic water pumping systems

Photovoltaic (PV) water pumping systems have been widely tested and assessed in Indonesia because of the deficiency of potable water in remote areas. Several different PV water pumping systems, such as a.c./d.c. with/without battery and various pumps, have been tested in the field. Further study, evaluation and classification of optimized PV water pumping systems is needed. Three of those pumping systems were installed in Sumba Island in 1983, in three adjacent villages with similar climate and environment conditions. Two of the installations had a.c. direct coupled systems and the other had d.c. The a.c. systems used a 3.65 kW_p PV generator each and the d.c. system used 5.76 kW_p. After comparing the performance data of both systems, it can be concluded that the a.c. system performs better and needs less maintenance on the pump. In May 1987, as a result of this evaluation, the 5.76 kW_p d.c. system was replaced by an a.c. one, and its capacity was increased to 9.22 kW_p. Meanwhile, the 3.65 kW_p a.c. system was increased to 3.88 kW_p.     

Determination ofp-cymene-2,3-diol, thymol, and carvacrol in different foodstuffs

p-Cymene-2,3-diol, carvacrol and thymol are components of thyme that exhibit antioxidant activities. The concentration of each substance was determined in different foodstuffs containing thyme extract. The stabilities ofp-cymene-2,3-diol, carvacrol and thymol were examined by heating lard containing thyme extract at temperatures from 80 °C to 160 °C.     

Effects of viscosities on the transient current in homeotropic nematic liquid crystal cells

Effects of the Leslie viscosity coefficients α_i (i = 1, 2, …, 5) of nematic liquid crystals (NLCs) with negative dielectric anisotropy (Δε < 0) on the electric-field-induced director reorientation in homeotropic NLC cells have been studied from the analysis of the transient current induced by step voltage application. The transient current in a homeotropic NLC cell with Δε < 0 was well reproduced by computer simulation, based on the theory of NLCs in which the flow effects and the free-slip boundary condition are taken into account. It is found that the response time of vertical alignment NLC displays is dominantly governed by α₂ and α₄ + α₅ of NLCs with Δε < 0.     

Evidence for a transitional period for development of persistence in infant rats.

Conducted 4 experiments with a total of 188 rat pups to test the hypothesis that rat pups can learn persistence at age 11 days but cannot express this learning in their behavior until they are a few days older. Exp I used a space-trial procedure to investigate the relative reinforcing effects of milk suckling, dry suckling, and contact without suckling at ages 11 and 14 days. Exp II used the Exp I procedure, manipulating schedule of reward at 2 ages and under 2 of the reward conditions. Exp III manipulated the dry suckling reward schedule in 11- and 14-day-old pups. Exp IV manipulated partial and continuous reinforcement on Day 11 but tested for persistence on Day 14. Results suggest the existence of a traditional period in neonatal rats for the learning of persistence. Partial reinforcement training with suckling on an anesthetized dam as reward induced greater persistence in extinction of the approach response than did continuous reinforcement in rat pups 14 days old but not in 11-day-old pups. Other aspects of this period of development are discussed. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ProsthesisWare: A new class of software supporting the activities of daily living.

Presents a case study of a 37-yr-old female patient with an expressive aphasia secondary to a traumatic brain injury. The development of successive approximations of a speech prosthesis for the S illustrated how new hardware and software capabilities permit the rapid iterative design and redesign of cognitive prosthesis tools. However, the rehabilitation infrastructure supporting microcomputer implementation needs to be developed. The emergence of ProsthesisWare, a class of rehabilitation software, constitutes an application of microcomputers that offers utilitarian prosthetic aids for activities of daily living for some people with cognitive impairments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Testwiseness as a factor in readiness test performance of young Mexican-American children.

Assessed the effects of training in test-taking skills on kindergarten children's performance on a school readiness test with a sample of 131 Spanish-speaking children from low socioeconomic backgrounds. Half of the Ss were trained in content-free test-taking skills, and half were provided comparable time in nondirected paper/crayon activities. All Ss were tested in both Spanish and English, with order of administration balanced. Trained Ss performed better than untrained Ss in both languages. Males were more influenced by training than were females, but overall females outperformed males. Spanish administration scores were higher than English administration scores. Order of test administration was significant in that performance in English was improved when the test was taken first in Spanish; no influence of English on subsequent performance was found. Findings support the hypothesis that test-wiseness is an important influence on test performance of young children from nonmajority backgrounds and should be taken into account in readiness assessment programs. (14 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Linear and widely linear filtering applied to iterative detection of generalized MIMO signals

To suppress the co-antenna interference in multiple input multiple output (MIMO) systems, an iterative receiver with a linear detector for complex symbols is investigated. We show that the considered generalized MIMO system, i.e., a system that transmits complex conjugate repetitions in addition to the pure data, requires the application of a widely linear (wl) detector. Awl detector consists of four real filters which are represented by two complex filters for the received signal and its complex conjugate, respectively. Furthermore, we present approximations of the detector that significantly reduce computational complexity with only little loss in frame-error rate performance. Simulation results show that the proposed MIMO system achieves large gains over standard solutions.     

Performance of Slotted ALOHA Random Access with Delay Capture and Randomized Time of Arrival

The application of the slotted ALOHA random access technique to a system using a spread spectrum waveform is described and analyzed. The technique takes advantage of the delay capture properties of spread spectrum waveforms and is shown to achieve excellent delay and throughput performance. System stability is maintained even in the face of severe fluctuations in user population or traffic loading such as may occur in a large population of mobile users.     

Diversity of lactic acid bacteria from Hussuwa, a traditional African fermented sorghum food

The diversity of lactic acid bacteria associated with Hussuwa fermentation, a Sudanese fermented sorghum food, was studied using a polyphasic taxonomical approach. Predominant strains could be well characterised based on a combination of phenotypic tests and genotypic methods such as ARDRA, rep-PCR and RAPD-PCR, as well as 16S rRNA gene sequencing of representative strains. Thus, the majority (128 of 220, 58.3%) of strains exhibited phenotypic properties typical of heterofermentative lactobacilli and of these, 100 strains were characterised more closely using the genotyping methods. The majority (97/100) strains could be characterised as Lactobacillus fermentum strains. Seventy-two of 220 strains (32.7%) showed phenotypic properties that are characteristic of pediococci. Of 41 selected strains investigated by genotyping techniques, 38 (92.7%) could be characterised as Pediococcus acidilactici strains, while three (7.3%) could be characterised as Pediococcus pentosaceus strains. The Hussuwa fermentation thus appears to be dominated by L. fermentum strains and P. acidilactici strains. For this reason, we selected representative and predominant strains as potential starter cultures for Hussuwa fermentation. These strains, L. fermentum strains BFE 2442 and BFE 2282 and P. acidilactici strain BFE 2300, were shown on the basis of RAPD-PCR fingerprinting to predominate in a model fermentation when used as starter cultures inoculated at 1 × 10⁶ CFU/g and to lower the pH of the fermentation to below pH 4.0 within 48 h. These cultures should be studied for further development as starter preparations in pilot scale studies in actual field fermentations.