Costs of reducing water use of concentrating solar power to sustainable levels: Scenarios for North Africa

Concentrating solar power (CSP) has the potential to become a leading sustainable energy technology for the European electricity system. In order to reach a substantial share in the energy mix, European investment in CSP appears most profitable in North Africa, where solar potential is significantly higher than in southern Europe. As well as sufficient solar irradiance, however, the majority of today's CSP plants also require a considerable amount of water, primarily for cooling purposes. In this paper we examine water usage associated with CSP in North Africa, and the cost penalties associated with technologies that could reduce those needs. We inspect four representative sites to compare the ecological and economical drawbacks from conventional and alternative cooling systems, depending on the local environment, and including an outlook with climate change to the mid-century. Scaling our results up to a regional level indicates that the use of wet cooling technologies would likely be unsustainable. Dry cooling systems, as well as sourcing of alternative water supplies, would allow for sustainable operation. Their cost penalty would be minor compared to the variance in CSP costs due to different average solar irradiance values.     

SeaWiFS on-orbit gain and detector calibrations: effect on ocean products

The NASA Ocean Biology Processing Group's Calibration and Validation Team has analyzed the mission-long Sea-Viewing Wide Field-of-View Sensor (SeaWiFS) on-orbit gain and detector calibration time series to verify that lunar calibrations, obtained at nonstandard gains and radiance ranges, are valid for Earth data collected at standard gains and typical ocean, cloud, and land radiances. For gain calibrations, a constant voltage injected into the postdetector electronics allows gain ratios to be computed for all four detectors in each band. The on-orbit lunar gain ratio time series show small drifts for the near infrared bands. These drifts are propagated into the ocean color data through the atmospheric correction parameter epsilon, which uses the 765/865 nm band ratio. An anomaly analysis of global mean normalized water-leaving radiances at 510 nm shows a small decrease over the mission, while an analysis of epsilon shows a corresponding increase. The drifts in the lunar time series for the 765 and 865 nm bands were corrected. An analysis of the revised water-leaving radiances at 510 nm shows the drift has been eliminated, while an analysis of epsilon shows a reduced drift. For detector calibrations, solar diffuser observations made by the individual detectors in each band allows the response of the detectors to be monitored separately. The mission-long time series of detector calibration data show that the variations in the response of the individual detectors are less than 0.5% over the mission for all bands except the 865 nm band, where the variations are less than 1%.     

Assessment of tilt capability for spaceborne global ocean colorsensors

The importance of tilt capability for Sun glint avoidance for future global ocean color missions was analyzed. The analyses focused on Sea-viewing Wide Field-of-view Sensor (SeaWiFS) mission, because its radiometric, orbital, and sensor characteristics are well defined. The analyses concentrated can two major questions: 1) does tilting to avoid Sun glint increase or decrease the total ocean coverage, and 2) at high latitudes far from the region of maximum Sun glint, should the sensor be tilted or untilted? For ocean coverage maximization, if the sensitivity of ocean color algorithms to Sun glint is of the same order as the error in the atmospheric correction algorithms, then a tilted sensor produces nearly 20 percent better coverage than an untilted one after 2 d in the absence of clouds, and 12 percent after 4 d including clouds. Thus, the tilt capability can improve the ocean coverage of future ocean color missions. At high latitudes differences in transmitted water-leaving radiance between tilted and untilted sensors were well within the algorithm errors. Furthermore, Sun glint radiances exceeding the algorithm errors occurred at high wind speeds as far as 70° from the solar declination, suggesting that sensors should remain in the tilted mode up to this limit     

Introducing fluorine-18 fluoromisonidazole positron emission tomography for the localisation and quantification of pig liver hypoxia

Fluorine-18 labelled fluoromisonidazole ([18F]FMISO) has been shown to accumulate in hypoxic tissue in inverse proportion to tissue oxygenation. In order to evaluate the potential of [18F]FMISO as a possible positron emission tomography (PET) tracer for imaging of liver tissue hypoxia, we measured the [18F]FMISO uptake in 13 domestic pigs using dynamic PET scanning. Hypoxia was induced by segmental arterial hepatic occlusion. During the experimental procedure the fractional concentration of inspired oxygen (FiO2) was set to 0.67 in group A (n=6) and to 0.21 in group B (n=7) animals. Before and after arterial occlusion, the partial pressure of O2 in tissue (TPO2) and the arterial blood flow were determined in normal flow and flow-impaired liver segments. Standardised uptake values [SUV=kBq tissue (in g) / body weight (in kg) x injected dose (in kBq)] for [18F]FMISO were calculated from PET images obtained 3 hours after injection of about 10 MBq/kg body weight [18F]FMISO. Immediately before PET scanning, the mean arterial blood flow was significantly decreased in arterially occluded segments [group A: 0. 41 (0.32-0.52); group B: 0.24 (0.16-0.33) ml min-1 g-1] compared with normal flow segments [group A: 1.05 (0.76-1.46); group B: 1.14 (0.83-1.57) ml min-1 g-1; geometric mean (95% confidence limits); P<0.001 for both groups]. After PET scanning, the TPO2 of occluded segments (group A: 5.1 (4.1-6.4); group B: 3.5 (2.6-4.9) mmHg] was significantly decreased compared with normal flow segments [group A: 26.4 (21.2-33.0); group B: 18.2 (13.3-25.1) mmHg; P<0.001 for both groups]. During the 3-h PET scan, the mean [18F]FMISO SUV determined in occluded segments increased significantly to 3.84 (3.12-4.72) in group A and 5.7 (4.71-6.9) in group B, while the SUV remained unchanged in corresponding normal liver tissue [group A: 1.4 (1.14-1. 71); group B: 1.31 (1.09-1.57); P<0.001 for both groups]. Regardless of ventilation conditions, a significant inverse exponential relationship was found between the TPO2 and the [18F]FMISO SUV (r2=0. 88, P<0.001). Our results suggest that because tracer delivery to hypoxic tissues was maintained by the portal circulation, the [18F]FMISO accumulation in the liver was found to be directly related to the severity of tissue hypoxia. Thus, [18F]FMISO PET allows in vivo quantification of pig liver hypoxia using simple SUV analysis as long as tracer delivery is not critically reduced.     

Recovery requirements of branch prediction storage structures in the presence of mispredicted-path execution

Execution along mispredicted paths may or may not affect the accuracy of subsequent branch predictions if recovery mechanisms are not provided to undo the erroneous information that is acquired by the branch prediction storage structures. In this paper, we study four elements of the Two-Level Branch Predictor: the Branch Target Buffer (BTB), the Branch History Register (BHR), the Pattern History Tables (PHTs), and the Return Address Stack (RAS). For each we determine whether a recovery mechanism is needed, and, if so, show how to design a cost-effective one. Using five benchmarks from the SPECint92 suite, we show that there is no need to provide recovery mechanisms for the BTB and the PHTs, but that performance is degraded by an average of 30% if recovery mechanisms are not provided for the BHR and RAS.     

Herstellung von Platten aus Altpapier unter Verwendung verschiedener Bindemittel

Ohne Zusammenfassung     

An automated method for navigation assessment for Earth survey sensors using island targets

An automated method has been developed for performing navigation assessment on satellite-based Earth sensor data. The method utilizes islands as targets which can be readily located in the sensor data and identified with reference locations. The essential elements are an algorithm for classifying the sensor data according to source, a reference catalogue of island locations, and a robust pattern-matching algorithm for island identification. The algorithms were developed and tested for the Sea-viewing Wide Field-of-view Sensor (SeaWiFS), an ocean colour sensor. This method will allow navigation error statistics to be automatically generated for large numbers of points, supporting analysis over large spatial and temporal ranges.     

麦草浆无氯漂白的研究

本文对麦草浆无氯漂白的可漂性能进行了研究，指出在保持纸浆具有良好的粘度下，用常规氧碱漂白和强化氧碱漂白分别可脱除残余木素达５０％和７０％以上，纸浆的白度可分别达到３８％ＩＳＯ和４９％ＩＳＯ左右。常规氧漂浆再用过氧化氢强化的氧漂继而可多脱除２０％～３０％的残余木素，纸浆白度高达６０％～６５％ＩＳＯ。麦草浆用ＴＣＦ漂白流程如ＯＯ／ＰＰ，在最终过氧化氢漂段的过氧化氢用量为２．０％时，可获得白度为７５％～８０％ＩＳＯ的纸浆，若采用单段带压的氧气和过氧化氢漂白，可将氧漂浆和本色浆漂到８０％ＩＳＯ的白度，且过氧化氢用量达３．５％～５．０％。考虑到ＴＣＦ漂白废水可逆流回用到碱回收，消除了漂白废水的污染，从而使漂白车间无废水排放。     

In vivo stimulation of connective tissue accumulation by the tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ in rat experimental wounds

The tripeptide-copper complex glycyl-L-histidyl-L-lysine-Cu2+ (GHK-Cu) was first described as a growth factor for differentiated cells. Recent in vitro data showed that it possesses several properties of a potential activator of wound repair. We investigated the effects of GHK-Cu in vivo, using the wound chamber model described previously (Schilling, J.A., W. Joel, and M.T. Shurley, 1959. Surgery [St. Louis]. 46:702-710). Stainless steel wire mesh cylinders were implanted subcutaneously on the back of rats. The animals were divided into groups that received sequential injections into the wound chamber of either saline (control group) or various concentrations of GHK-Cu. At the end of the experiments, rats were killed, wound chambers were collected, and their content was analyzed for dry weight, total proteins, collagen, DNA, elastin, glycosaminoglycans, and specific mRNAs for collagens and TGF beta. In the GHK-Cu-injected wound chambers, a concentration-dependent increase of dry weight, DNA, total protein, collagen, and glycosaminoglycan contents was found. The stimulation of collagen synthesis was twice that of noncollagen proteins. Type I and type III collagen mRNAs were increased but not TGF beta mRNAs. An increase of the relative amount of dermatan sulfate was also found. A control tripeptide, L-glutamyl-L-histidyl-L-proline, had no significant effect. These results demonstrate that GHK-Cu is able to increase extracellular matrix accumulation in wounds in vivo.