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91.
The ongoing human-induced emission of carbon dioxide (CO2) threatens to change the earth's climate. One possible way of decreasing CO2 emissions is to apply CO2 removal, which involves recovering of carbon dioxide from energy conversion processes and storing it outside the atmosphere. Since the 1980's, the possibilities for recovering CO2 from thermal power plants received increasing attention.In this study possible techniques of recovering CO2 from large-scale industrial processes are assessed.In some industrial processes, e.g. ammonia production, CO2 is recovered from the process streams to prevent it from interfering with the production process. The CO2 thus recovered can easily be dehydrated and compressed, at low cost. In the iron and steel industry, carbon dioxide can be recovered from blast furnace gas. In the petrochemical industry CO2 can be recovered from flue gases, using low-temperature heat for the separation process.Carbon dioxide can be recovered from large-scale industrial processes and in some cases the cost of recovery is significantly less than CO2 recovery from thermal power plants. Therefore this option should be studied further and should be considered if carbon dioxide removal is introduced on a wide scale. 相似文献
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The experimental programme of Southard and Mackintosh (1981) provides a definitive refutation of the autosuspension criterion as it was originally defined. A simple energy budget for dilute two-phase flow is derived from continuum theory of mixtures; it shows that Bagnold's criterion is based on an arbitrary comparison of two elements of the complete two-phase system. It is recommended that facile, ab hoc criteria for the behaviour of such complex flows be avoided in favour of analyses based on fundamental equations of motion. 相似文献
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96.
A study on two closed salt lake basins, Tal Chapar and Parihara in the eastern margin of the Thar Desert, Rajasthan, was carried
out to unravel late Quaternary geomorphic evolution of these saline lakes. Both lakes are elliptical in shape bordered by
stabilised dunes, and are oriented in a NE-SW direction, i.e., in the direction of the prevailing summer monsoon wind. Both
lakes have been formed in the wind-shadow zones of isolated hills of Precambrian quartzite. Our study indicates that the late
Quaternary sediments in the lakes began with the cyclic deposition of laminated fine silt layers (0.5 m thick), rich in organic
matter, alternating with ripple cross-bedded sand layers (each ∼1.5–2 m thick). Sand layers that are moderately sorted are
separated by laminated silt-clay layers with gypsum/calcite and this unit occurs in the upper most 4 m sequence in deeper
sections. The presence of gypsum crystals within the laminated sediments suggests a high concentration of Ca in the inflowing
water.
At Parihara Lake the organic carbon-rich sediments at 95 cm depth was dated to 7,375 + 155/−150 year BP. At Tal Chapar radiocarbon
dates of 7,190 + 155/−150 and 9,903 + 360/−350 was obtained from the sediments rich in organic carbon occurring at a depth
of 1.35 m and 1.80 m, respectively. The study reveals strong hydrologic oscillations during the past ∼14,000 year BP (13,090 + 310/−300 year
BP).
Quaternary geomorphic processes, especially the strong aeolian processes during dry climatic phases, played a major role in
the formation of the lake basins, as well as the fringing linear dunes. Geochemical and mineralogical analyses of the lacustrine
sediments, supported by radiocarbon dates indicate the existence of an ephemeral lake earlier than ∼13,000 year BP as sediments
began to be deposited in a lacustrine environment implying sustained runoff in the catchments. A freshwater lake formed between
9,000 year and 7,000 year BP. The lake dried periodically and this strong fluctuating regime continued until about ∼7,000 year
BP. Mid-Holocene was wet and this was possibly due to higher winter rains A saline lake existed between 6,000 year and 1,300 year
BP and finally present day semi arid conditions set in since 1,200 year BP. Remnants of a habitation site (hearth and charred
bones) on stabilised dune at Devani near Tal Chapar were dated to 240 ± 120 year, while that at Gopalpura was dated to 335 ± 90 year.
These historical sites on stabilised dunes were, according to the local accounts, settlements of people who used the lake
brine for manufacturing salt. 相似文献
97.
Location-based services: technical and business issues 总被引:13,自引:0,他引:13
Geographical Information System (GIS) and Global Positioning System (GPS) technologies are expanding their traditional applications
to embrace a stream of consumer-focused, location-based applications. Through an integration with handheld devices capable
of wireless communication and mobile computing, a wide range of what may be generically referred to as 'Location-Based Services'
(LBS) may be offered to mobile users. A location-based service is able to provide targeted spatial information to mobile workers
and consumers. These include utility location information, personal or asset tracking, concierge and route-guidance information,
to name just a few of the possible LBS. The technologies and applications of LBS will play an ever increasingly important
role in the modern, mobile, always-connected society. This paper endeavours to provide some background to the technology underlying
location-based services, and to discuss some issues related to developing and launching LBS. These include whether wireless
mobile technologies are ready to support LBS, which mobile positioning technologies can be used and what are their shortcomings,
and how GIS developers manipulate spatial information to generate appropriate map images on mobile devices (such as cell phones
and PDAs). In addition, the authors discuss such issues as interoperability, privacy protection and the market demand for
LBS.
Electronic Publication 相似文献
98.
DAI LiwenHAN ShaoweiChris Rizos 《地球空间信息科学学报》2001,4(4):9-18
1 IntroductionReal_timekinematicGPSprecisepositioninghasbeenplayinganincreasingroleinbothsurveyingandnavigation ,andhasbecomeanessentialtoolforpreciserelativepositioning .However,reliableandcorrectambiguityresolutiondependsonobserva tionsuponalargenumbe… 相似文献
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100.
Techniques are described in this paper for improving the Ambiguity Function Method (AFM) for differential GPS positioning using phase observations, (a) that take advantage of optimal dual-frequency observable combinations to improve thereliability of the AFM, and (b) that significantly shorten the computation time necessary for the AFM. The procedure can be used for kinematic positioning applications if a Kalman filter predicted position is accurate enough as an initial position for the suggested AFM searching procedure, or pseudokinematic mode using say a triple-difference solution as an initial position for static positioning if the baseline length is short (typically <5km). 相似文献