Study of hourly and daily solar irradiation forecast using diagonal recurrent wavelet neural networks

An accurate forecast of solar irradiation is required for various solar energy applications and environmental impact analyses in recent years. Comparatively, various irradiation forecast models based on artificial neural networks (ANN) perform much better in accuracy than many conventional prediction models. However, the forecast precision of most existing ANN based forecast models has not been satisfactory to researchers and engineers so far, and the generalization capability of these networks needs further improving. Combining the prominent dynamic properties of a recurrent neural network (RNN) with the enhanced ability of a wavelet neural network (WNN) in mapping nonlinear functions, a diagonal recurrent wavelet neural network (DRWNN) is newly established in this paper to perform fine forecasting of hourly and daily global solar irradiance. Some additional steps, e.g. applying historical information of cloud cover to sample data sets and the cloud cover from the weather forecast to network input, are adopted to help enhance the forecast precision. Besides, a specially scheduled two phase training algorithm is adopted. As examples, both hourly and daily irradiance forecasts are completed using sample data sets in Shanghai and Macau, and comparisons between irradiation models show that the DRWNN models are definitely more accurate.     

Remote Monitoring of Daily Nocturnal Hemodialysis

Daily nocturnal hemodialysis (DNHD) is a new variant of home hemodialysis that allows patients to dialyze at home, at night, while they sleep, providing longer duration and greater frequency of treatments. This paper describes a 3‐year experience with remote monitoring of DNHD patients over the Internet, and we review the remote monitoring experience of the Toronto program, which pioneered DNHD. Technology, structure, and costs are reviewed. Remote monitoring enhanced safety, accuracy of data collection, patient catchment area, and the overall comfort of patients, providers, and regulators.     

Global ESRD Costs Associated with a Short Daily Hemodialysis Program in the United States

In spite of the growing evidence that daily hemodialysis (DHD) improves clinical outcomes and quality of life, the additional dialysis costs are not currently reimbursed in the United States. Nor have there been reports of the effects of DHD on end-stage renal disease (ESRD) global costs, which would help predict the financial impact of DHD on the ESRD program. Since 1996, 22 patients (20 in-center, 2 home) have switched from conventional thrice-weekly dialysis to short, daily dialysis with six treatments per week. Eighteen patients started for medical indications, and four started for nonmedical reasons. Causes of ESRD were the following: diabetes mellitus (6), hypertension (4), glomerulonephritis (6), hereditary (2), and other (4). Mean age was 56 ± 16 years. Patients had an average of 3.3 major comorbidities. Weekly conventional HD dialysis times were divided into six DHD treatments, each 2.0 ± 0.3 hours. Weekly Kt/V remained unchanged. Twenty-two patients were followed on DHD for 220 patient-months: 7 patients died after 1.8 ± 1.3 months, 2 were transplanted at 4.3 ± 3.2 months, and 2 discontinued DHD at 3.6 ± 4.8 months. Eleven patients remain on DHD at 17.4 ± 8.3 months. Actual costs per extra dialysis session are as follows: $14.30 for supplies and $3.20 for labor for setup/cleanup time (15 minutes at $12.80/hour). Annualized DHD savings are based on comparison of doses of epoetin alpha (Epogen) and blood pressure medication at the start and after 12 months of DHD. Hospitalization rates include all enrolled patients, comparing rates for the 12 months prior to DHD with the first year on DHD, or annualized rates for those on DHD less than one year. Cost assumptions are $9/ 1000 U Epogen, $1/blood pressure pill, and $1200/per day of hospitalization. Extra transportation costs were covered by the patients. No increased access problems were observed. For patients on short DHD longer than 12 months, supply and labor costs increased to $2733/patient/year; however, Epogen use was reduced 55%, and blood pressure medications were reduced 40%. For all patients who switched to DHD, hospitalization rates were reduced 24%. This resulted in a net savings of about $4241/patient/ year after 12 months on DHD. Overall ESRD costs were substantially decreased on DHD. These cost savings must be passed on to providers before DHD becomes more widely available.     

Blood Access Outcomes Associated with Short Daily Hemodialysis

With the growing number of reports that daily hemodialysis (DHD) improves clinical outcomes and quality of life, there has been increased interest in the effects of more frequent venipunctures on blood accesses. Since 1996, we have converted 30 patients (27 in‐center, 3 home) from conventional 3/week dialysis to short, daily, 6/week dialysis (sDHD). Twenty‐five patients started for medical indications. End‐stage renal disease (ESRD) causes were diabetes mellitus (in 7), hypertension (6), glomerulonephritis (8), hereditary nephritis (2), and other (7). Mean (±SD) age was 57 ± 16 years. Patients had an average of 3.8 major comorbidities in addition to ESRD. Thirty patients were followed on sDHD for 388 patient‐months: 9 patients died after 4.2 ± 6.7 months, 3 were transplanted at 5.4 ± 2.2 months, and 3 were disenrolled at 9.3 ± 10.5 months. Fifteen patients remain on sDHD at 20.4 ± 14.1 months. Access problems for the 12 months prior to sDHD were compared to those that occurred while the patient was on sDHD. Problems were tracked by access type. There were 40 different accesses in 30 patients with a cumulative 28.07 access‐years pre‐DHD; 24 of these accesses were artificial bridge grafts (ABG) of either polytetrafluoroethylene or bovine material. There were 27 access problems pre‐DHD, or 0.962 problems per access‐year. On sDHD these same 30 patients had 41 accesses for 34.44 access‐years; 23 of these were ABGs. There were 31 access problems or 0.900 problems per access‐year. There were no significant differences in access problems comparing pre‐DHD with on‐sDHD, either in aggregate or when analyzed by access type. After 39 months of observation, there does not appear to be an increase in blood access problems when patients are converted from conventional dialysis to sDHD.     

DCS控制系统中UPS电源的配置使用和维护

介绍了DCS控制系统中UPS电源的配置选用和工作原理以及UPS电源正确的开关机步骤和维护注意事项。     

浅析日调节水库装机容量选择

通过对桃江枫坑口日调节水库装机容量选择的分析论证，选定了符合该电力系统负荷特性，经济、合理的装机容量。     

浅谈现阶段如何推行HSE

根据胜利油田建立实施HSE管理体系工作的现状,提出现阶段推行HSE管理体系要做好五方面的工作。在日常管理工作中,要做到高标准、高质量、严要求、严考核。     

深圳抽水蓄能电站上水库主坝坝型选择

本文着重介绍了在可研究性阶段,通过对深圳抽水蓄能电站上水库主坝设计过程中坝型选择的相关因素的分析,确定其大坝类型的过程。     

薄膜式LNG运输船温度场研究

液化天然气运输船液货舱热维护系统是一个结构复杂的、具有第三类边界条件的、多层平壁的稳态导热与自然对流及辐射换热相互耦合的三维复杂传热系统。针对这一复杂系统，考虑了船体主要构件、骨材、空腔空气对流、表面间的辐射对换热的影响，建立了数学模型，并给出了基于通用软件ANSYS的数值计算方法；还以某艘LNG运输船为例，进行了温度场的有限元分析。结果表明，所给出的对LNG运输船液货舱热维护系统的热分析方法是有效的。     

Aluminium content of Spanish infant formula

Levels of aluminium in 82 different infant formulae from nine different manufacturers in Spain were determined by acid-microwave digestion and graphite furnace atomic absorption spectrophotometry. The influence of aluminium content in tap water in reconstituted powder formulae was examined and an estimate was made of the theoretical toxic aluminium intake in comparison with the provisional tolerable weekly intake (PTWI). Possible interactions between aluminium and certain essential trace elements added to infant formulations have been studied according to the type or main protein-based infant formula. In general, the infant formulae contained a higher aluminium content than that found in human milk, especially in the case of soya, preterm or hydrolysed casein-based formulae. Standard formulae gave lower aluminium intakes amounting to about 4% PTWI. Specialized and preterm formulae resulted in a moderate intake (11-12 and 8-10% PTWI, respectively) and soya formulae contributed the highest intake (15% PTWI). Aluminium exposure from drinking water used for powder formula reconstitution was not considered a potential risk. In accordance with the present state of knowledge about aluminium toxicity, it seems prudent to call for continued efforts to standardize routine quality control and reduce aluminium levels in infant formula as well as to keep the aluminium concentration under 300 μg l^-1 for all infant formulae, most specifically those formulae for premature and low birth neonates.