Climate Control in Mediterranean Greenhouses

As climate control in greenhouses directly affects crop yields, there is an increasing trend for advancements in environmentally controlled agricultural-production techniques. In the Mediterranean region, the temperatures during the period from December to February are below 12°C when the daily total radiation 8.4 MJ/m2day. Based on the region?s climate data, greenhouses require heating during the period from November to March, ventilation and shading from February to May and cooling from June to September. In order to maintain day and night temperatures of 18/16°C, annual heat energy requirement of PE greenhouses is 95-256 kWh/m2. In view of environment and production costs, conservation of heating energy is as important as heating itself. Heat energy saving is about 37% when energy curtains are used. Greenhouse temperature can be increased by 8°C in palliative non-heated greenhouses where energy curtains and water mattresses are used in addition to passively used solar energy. Ventilation openings at the roofs of these greenhouses should adequately be 20-25%. When outside noon-time temperature is above 30°C in June, evaporative cooling of greenhouse is essential. Depending on outside humidity and volume of exchanged air for cooling, a temperature difference of 6°C can be achieved with evaporative cooling of greenhouses in August

Nonhyperbolic reflection moveout for orthorhombic media

Reflection moveout in azimuthally anisotropic media is not only azimuthally dependent but it is also nonhyperbolic. As a result, the conventional hyperbolic normal moveout (NMO) equation parameterized by the exact NMO (stacking) velocity loses accuracy with increasing offset (i.e., spreadlength). This is true even for a single-homogeneous azimuthally anisotropic layer. The most common azimuthally anisotropic models used to describe fractured media are the horizontal transverse isotropy (HTI) and the orthorhombic (ORT). Here, we introduce an analytic representation for the quartic coefficient of the Taylor’s series expansion of the two-way traveltime for pure mode reflection (i.e., no conversion) in arbitrary anisotropic media with arbitrary strength of anisotropy. In addition, we present an analytic expression for the long-spread (large-offset) nonhyperbolic reflection moveout (NHMO). In this study, special attention is given to Pwave propagation in orthorhombic media with horizontal interfaces. The quartic coefficient, in general, has a relatively simple form, especially for shear wave propagation. The reflection moveout for each shear-wave mode in a homogeneous orthorhombic medium is purely hyperbolic in the direction normal to the polarization. In addition, the nonhyperbolic portion of the moveout for shear-wave propagation reaches its maximum along the polarization direction, and it decreases rapidly away from the direction of polarization. Hence, the anisotropy-induced nonhyperbolic reflection moveout for shear-wave propagation is significant in the vicinity of the polarization directions. In multilayered azimuthally anisotropic media, the NMO (stacking) velocity and the quartic moveout coefficient can be calculated with good accuracy using Dix-type averaging (e.g., the known averaging equations for VTI media). The interval NMO velocities and the interval quartic coefficients, however, are azimuthally dependent. This allows us to extend the nonhyperbolic moveout (NHMO) equation, originally designed for VTI media, to more general horizontally stratified azimuthally anisotropic media. Numerical examples from reflection moveout in orthorhombic media, the focus of this paper, show that this NHMO equation accurately describes the azimuthally-dependent P-wave reflection traveltimes, even on spreadlengths twice as large as the reflector depth. This work provides analytic insight into the behavior of nonhyperbolic moveout, and it has important applications in modeling and inversion of reflection moveout in azimuthally anisotropic media.Massachusetts Institute of Technology. Earth Resources LaboratorySaudi Aramc

Studi Perbandingan Arsitektur Sistem I&c Pltn Generasi III Epr 1600 Dengan Us-apwr 1700

STUDI PERBANDINGAN ARSITEKTUR SISTEM I&C PLTN GENERASI III EPR 1600 DENGAN US-APWR 1700. Dalam rangka mendukung program pemerintah di bidang penelitian dan pengembangan energi nuklir, maka dilakukan studi perbandingan arsitektur sistem instrumentasi dan kendali (Instrumentation & Control, I&C) PLTN Generasi III EPR 1600 dengan US-APWR 1700. Sistem I&C adalah salah satu sistem pendukung operasi PLTN sehingga beroperasi dengan aman dan terkendali. Studi ini membandingkan beberapa parameter struktur inti dari arsitektur sistem I&C yang terkait erat dengan persyaratan sistem keselamatan operasi pembangkit. Metodologi yang digunakan dalam melaksanakan kegiatan ini adalah studi literatur, pengumpulan data, serta melakukan kajian dan analisis. Dari studi ini diperoleh hasil yang menunjukkan bahwa antara PLTN EPR 1600 dengan PLTN US-APWR 1700 banyak memiliki kesamaan, yaitu keduanya menerapkan teknologi arsitektur I&C digital yang sudah terkomputerisasi penuh dengan tingkat keselamatan tinggi berdasarkan kode standar persyaratan desain yang bersumber dari kode standar Amerika Serikat. Beberapa perbedaan yang agak menonjol antara keduanya adalah pada pengelompokan sistem safety-related dan non safety-related, sistem kendali dan pemantauan, beberapa pendukung sistem konsep pertahanan berlapis dan beberapa pendukung sistem keselamatan I&C

Pemakaian Pupuk Organik Cair sebagai Dekomposer dan Sumber Hara Tanaman Padi (Oriza Sativa L.)

A research to determine the effects of liquid organic fertilizer as a decomposer and nutrition source on the growth of rice plant (Oriza sativa L.). This research was conducted in Wirokerten, Botokenceng, Bantul, Yogyakarta. Field experiment was arranged using Randomized Completely Block Design with 2 factors and three replications. The first factor was liquid organic fertilizer, consist of liquid organic fertilizer and witout liquid organic fertilizer. The second factor was the doses of SRI, consist of 25% SRI, 50% SRI, 75% SRI and 100% SRI (urea fertilizer 350 kg/ha, 150 kg/ha of SP-36 fertilizer and 150 kg/ha of KCl fertilizer). The result showed that the liquid organic fertilizer with dose 10 l/ha macro fertilizer and 5 l/ha micro fertilizer were not significantly increased the growth and yield of rice plant. Liquid organic fertilizer with dose 75% SRI was significantly increased the leaf number than dose of 25% and 100% SRI. Doses 25% and 100% of SRI with application the liquid organic fertilizer was significantly increased the weight of 1000 seeds. Doses of SRI was not significantly increased the rice yield per hectar

A Comparison Of Scattering From 2-D And 3-D Rough Interface

In this paper we compared scattered waves from 2-D and 3-D interface structures. The modeling technique is the 3-D time domain finite difference method. The scheme is second-order accurate in time and fourth-order accurate in space. It is implemented on a massively parallel nCUBE computer. In order to investigate the characteristics of 2-D and 3-D rough surface scattering, we consider an acoustic-elastic boundary, which is described by a Gaussian autocorrelation function. The F-K analysis of reflected signals shows that 2-D scattering generates similar amounts of forward and back scattering, while in the 3-D case, more forward and less back scattering. The 3-D effects also show larger reflected energy than the 2-D case, especially near the normal incident. The out-of-plane scatterings are clearly demonstrated on the F-K spectra in the 3-D case. In the 2-D simulations, we have to keep in mind that it tends to overestimate the amount of backscattering energy.ERL/nCUBE Geophysical Center for Parallel ProcessingUnited States. Air Force Office of Scientific Research (Contract F49620-941-0282

Inhomogeneities in the Earth's Mantle

Using seismic body and surface waves, the velocity structure of the Earth's mantle is determined with the emphasis on regions of anomalous variations (so-called ‘discontinuities’). In the upper mantle, the interpretation of Rayleigh and Love wave dispersion curves yields shear velocity profiles with discontinuities at depths 350 km and 700 km, and a low-velocity zone extending to 350km. In the lower mantle P-velocity profile is determined from dt/dΔ measurements using large aperture seismic array and travel times from Long Shot nuclear explosion for the Japan-Kuriles-Aleutian-Montana path. The velocity structure shows anomalous gradients or ‘discontinuities’ at depths 700, 1200 and 1900km, indicating that the lower mantle is not homogeneous. Lateral variations of the velocity structures are investigated. For the upper mantle studies the Earth is divided into three regions: oceanic areas, continental shields, and tectonic zones. Pure path phase velocities of Love waves are extracted from the composite dispersion data. The pure path shear velocity profiles obtained from these data are characterized by lower velocities under the oceans in the uppermost portion of the mantle. Shields have the highest velocities. These velocity differences are interpreted in terms of temperature variations. At a depth of 110 km the temperature of the oceanic mantle is higher (by 100–500° C depending on the temperature coefficient of the velocity) than that of the mantle under the shields. The presence of lateral heterogeneities in the mantle is demonstrated qualitatively by the differences of dt/dΔ vs Δ curves for two separate paths. Undulations of the geoid as determined from satellite observations are investigated for determining the sources of the anomalies. It is concluded that the main sources of lateral density variations must be in the mantle at depths greater than about 100km