Hidraul : suatu penyelesaian

Buku ini mengandungi beberapa bab iaitu kandungan: prakata, catatan sejarah, bab 1 ciri fizik bendalir, pendahuluan, takrifan, unit, bab 2 statik bendalir, perubahan keamatan tekanan, pengukuran tekanan, daya pada satah dan permukaan melengkung, ketimbulan, bab 3 hukum aliran bendalir, pengelasan jenis aliran, bab 4 penggunaan hukum aliran bendalir, garis tenaga dan garis gred hidraul, meter venturi, tiub pitot, bab 5 analisis bermatra, pengenalan, kaedah rayleigh, kaedah buckingham–p, bab 6 aliran dalam paip, persamaan darcy dan chezy, aliran lamina dalam paip, pengenalan kepada aliran lapisan sempadan dan gelora, bab 7 aliran seragam di saluran, seksyen ekonomis, tenaga tentu, aliran melewati suatu bonjolan di dasar, bab 8 aliran berubah bertahap di saluran, analisis aliran berubah bertahap, pengelasan lengkung air balik, analisis susuk dan titik kawalan, bab 9 model hidraul permukaan terbuka, hukum pengawalan model, penentuan skala model apabila kesasaran diambil kira, penentuan skala apabila pencetekan diambil kira, bab 10 aliran unggul boleh mampatpersamaan tenaga, halaju bunyi, tekanan dan suhu genangan, bab 11 aliran unggul dan nyata, mekanik pemisahan aliran, geseran dan hela seretan, edaran dan lif, bab 12 paluan air, penutupan injap seketika, penentuan tekanan lebih serta penutupan injap cepat dan perlahan

The International Urban Energy Balance Models Comparison Project: First Results from Phase 1

A large number of urban surface energy balance models now exist with different assumptions about the important features of the surface and exchange processes that need to be incorporated. To date, no com- parison of these models has been conducted; in contrast, models for natural surfaces have been compared extensively as part of the Project for Intercomparison of Land-surface Parameterization Schemes. Here, the methods and first results from an extensive international comparison of 33 models are presented. The aim of the comparison overall is to understand the complexity required to model energy and water exchanges in urban areas. The degree of complexity included in the models is outlined and impacts on model performance are discussed. During the comparison there have been significant developments in the models with resulting improvements in performance (root-mean-square error falling by up to two-thirds). Evaluation is based on a dataset containing net all-wave radiation, sensible heat, and latent heat flux observations for an industrial area in Vancouver, British Columbia, Canada. The aim of the comparison is twofold: to identify those modeling ap- proaches that minimize the errors in the simulated fluxes of the urban energy balance and to determine the degree of model complexity required for accurate simulations. There is evidence that some classes of models perform better for individual fluxes but no model performs best or worst for all fluxes. In general, the simpler models perform as well as the more complex models based on all statistical measures. Generally the schemes have best overall capability to model net all-wave radiation and least capability to model latent heat flux

Surface Energy Budgets of Arctic Tundra During Growing Season

This study analyzed summer observations of diurnal and seasonal surface energy budgets across several monitoring sites within the Arctic tundra underlain by permafrost. In these areas, latent and sensible heat fluxes have comparable magnitudes, and ground heat flux enters the subsurface during short summer intervals of the growing period, leading to seasonal thaw. The maximum entropy production (MEP) model was tested as an input and parameter parsimonious model of surface heat fluxes for the simulation of energy budgets of these permafrost‐underlain environments. Using net radiation, surface temperature, and a single parameter characterizing the thermal inertia of the heat exchanging surface, the MEP model estimates latent, sensible, and ground heat fluxes that agree closely with observations at five sites for which detailed flux data are available. The MEP potential evapotranspiration model reproduces estimates of the Penman‐Monteith potential evapotranspiration model that requires at least five input meteorological variables (net radiation, ground heat flux, air temperature, air humidity, and wind speed) and empirical parameters of surface resistance. The potential and challenges of MEP model application in sparsely monitored areas of the Arctic are discussed, highlighting the need for accurate measurements and constraints of ground heat flux.Plain Language SummaryGrowing season latent and sensible heat fluxes are nearly equal over the Arctic permafrost tundra regions. Persistent ground heat flux into the subsurface layer leads to seasonal thaw of the top permafrost layer. The maximum energy production model accurately estimates the latent, sensible, and ground heat flux of the surface energy budget of the Arctic permafrost regions.Key PointThe MEP model is parsimonious and well suited to modeling surface energy budget in data‐sparse permafrost environmentsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150560/1/jgrd55584.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150560/2/jgrd55584_am.pd

Impact of land cover changes on the South African climate

The Joint UK Land Environmental Simulator (JULES) was run offline to investigate the sensitivity of land surface type changes over South Africa. Sensitivity tests were made in idealised experiments where the actual land surface cover is replaced by a single homogeneous surface type. The vegetation surface types on which some of the experiments were made are static. Experimental tests were evaluated against the control. The model results show among others that the change of the surface cover results in changes of other variables such as soil moisture, albedo, net radiation and etc. These changes are also visible in the spin up process. The model shows different surfaces spinning up at different cycles. Because JULES is the land surface model of Unified Model, the results could be more physically meaningful if it is coupled to the Unified Model