Gravitational clustering of galaxies in an expanding universe

We inquire the phenomena of clustering of galaxies in an expanding universe from a theoretical point of view on the basis of thermodynamics and correlation functions. The partial differential equation is developed both for the point mass and extended mass structures of a two-point correlation function by using thermodynamic equations in combination with the equation of state taking gravitational interaction between particles into consideration. The unique solution physically satisfies a set of boundary conditions for correlated systems and provides a new insight into the gravitational clustering problem.     

Peculiar motions of galaxy clusters: correlation function approach

The correlation function theory on the basis of prescribed boundary conditions provides a deeper understanding in studying the dynamical parameters of galaxy clusters. The approach approximates that the moderate dense systems discussed by a two point correlation function is helpful for describing the dynamical nature of galaxy clusters. The projected theory of two point correlation function for point mass and extended mass structures can be used an alternative tool in measuring the average peculiar motion and temperature profile of galaxy clusters.     

Imaging of Stratigraphic Pinch-Out Traps Within the Lower-Cretaceous Shaly-Sandstone System,Pakistan, Using 3D Quantitative Seismic Inverted Porosity–Velocity Modeling

Incised valleys form excellent stratigraphic pinch-out traps. Traditional seismic data analysis techniques fail to predict quantitatively the porous and low-velocity sand-fills for incised valleys. The 3D quantitative seismic inverted porosity–velocity (3DQSIPV) analysis was applied in the Indus Basin, SW Pakistan. The reflection strength attribute better portrayed the reservoir sandstone and faults compared to seismic amplitude attribute. The sweetness-based continuous wavelet transform authenticated the development of the stratigraphic play. The 17 Hz amplitude delineated the non-porous seal and porous reservoirs of sand-filled incised valley and strand plain, and faults. The integrated model of seismic attributes categorizes the reservoir and seal constituents. The petrophysical modeling corroborated the gas-bearing “sweet-spots” within the stratigraphic-based dynamical system. The facies modeling predicted the for coarse-grained sandstone and fine-grained shales, depositional environments, fluctuations of sea level and their impacts on the overall development of stratigraphic plays. The predicted density and P-wave velocity for the sandstone-filled incised valley of the lowstand system tract were?~?1.4–1.75 g/cc and?~?3217–3802 m/s, respectively. The predicted density and P-wave velocity for the sealing shales facies of strand plain of transgressive system tract were?~?1.9–2.1 g/cc and 2.55–2.7 g/cc and 3900–4700 m/s, respectively. The 3DQSIPV predicted?>?25% porosity and?~?3300 m/s velocity of reservoirs in the west. The eastern zones shows?<?12% porosity and high velocity of?~?4580 m/s. Cross-plots of porosity, velocity, and thickness showed correlation coefficients of R²?>?0.90 for inverted velocity. This workflow may serve as an analogue for the remaining oil and gas fields of the Indus Basins of Pakistan and similar geological settings of divergent plate margins.

     

Preparation of magnetic microgels for catalytic reduction of 4-nitrophenol and removal of methylene blue from aqueous medium

This work describes the synthesis of poly(acrylic acid) microgels and fabrication of magnetic cobalt nanoparticles in the prepared microgels. Cobalt nanoparticles were fabricated by loading the cobalt (II) ions in microgels from aqueous solution and their subsequent reduction with sodium borohydride (NaBH₄). Bare and composite microgels were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. The catalytic properties of the prepared microgel composites were investigated by using them as catalyst for the reduction of 4-nitrophenol and methylene blue. The effect of temperature and catalyst dose on the rate of reduction of these toxic pollutants was investigated. The reusability of prepared catalysts was also studied for the five consecutive cycles, and an increase in catalytic activity was observed after every cycle. The prepared bare and magnetic microgels were found as very effective adsorbent for the removal of methylene blue from aqueous medium. Very rapid adsorption rate was found for the removal of methylene as its 100 mg was adsorbed on per gram of dried hydrogels in about 25 min. The effects of different parameters like amount of adsorbate and concentration of adsorbent on the adsorption process were studied. Langmuir, Freundlich and Temkin adsorption isotherms were applied, and it was found that adsorption of MB follows Freundlich model better than others. Furthermore, pseudo-first-order and pseudo-second-order kinetic models were also applied and adsorption of MB was found to abide by pseudo-second-order kinetics.     

A fundamental theorem for eco-environmental surface modelling and its applications

We propose a fundamental theorem for eco-environmental surface modelling(FTEEM) in order to apply it into the fields of ecology and environmental science more easily after the fundamental theorem for Earth's surface system modeling(FTESM). The Beijing-Tianjin-Hebei(BTH) region is taken as a case area to conduct empirical studies of algorithms for spatial upscaling, spatial downscaling, spatial interpolation, data fusion and model-data assimilation, which are based on high accuracy surface modelling(HASM), corresponding with corollaries of FTEEM. The case studies demonstrate how eco-environmental surface modelling is substantially improved when both extrinsic and intrinsic information are used along with an appropriate method of HASM. Compared with classic algorithms, the HASM-based algorithm for spatial upscaling reduced the root-meansquare error of the BTH elevation surface by 9 m. The HASM-based algorithm for spatial downscaling reduced the relative error of future scenarios of annual mean temperature by 16%. The HASM-based algorithm for spatial interpolation reduced the relative error of change trend of annual mean precipitation by 0.2%. The HASM-based algorithm for data fusion reduced the relative error of change trend of annual mean temperature by 70%. The HASM-based algorithm for model-data assimilation reduced the relative error of carbon stocks by 40%. We propose five theoretical challenges and three application problems of HASM that need to be addressed to improve FTEEM.     

New paleomagnetic results from the northern margin of the Kohistan Island Arc

Different phases of remanent magnetizations have been identified in the Cretaceous–Tertiary rocks collected from the northern margin of the Kohistan Island Arc, northern Pakistan. Among them, a magnetite-related component is recognized as the most useful one because of its relatively stable behaviour and widespread presence in the volcanics and red beds. Calculation of mean direction for this component reveal two visible groupings in terms of paleomagnetic directions (Yasin + Baris Group: D?=?341.6º, I?=?10.6º, α ₉₅?=?23.3 º, k?=?11.7, N?=?5; Sandhi Group: D?=?28.4º, I?=??27.4º, α ₉₅?=?32.5 º, k?=?8.96, N?=?4). The fold tests applied to both these groups are inconclusive, indicating a syn-folding to post-folding origin for this component. A set of inclinations from this study provide new insight into post-collision northward displacement of the Kohistan Arc with respect to its surrounding terranes. Reliability of the paleomagnetic declinations from this study is not fully guaranteed, but when compared with previously reported paleomagnetic directions, a systematic increase in counter-clockwise deflections towards west has been detected along this paleo-island arc. This trend of declinations is well matched with the extrusion model of Asia, where counter-clockwise rotation has been suggested for the tectonic terranes around Western Himalaya. Another important observation is a divergence in paleomagnetic declinations across the rivers, which may indicate the presence of faulted zones under the cover of flowing water. This aspect can be compared to recent geological interpretations that Kohistan may not have acted as a rigid block following its collision with India but may have been deformed through localized shears and faults.     

Detection of fluvial sand systems using seismic attributes and continuous wavelet transform spectral decomposition: case study from the Gulf of Thailand

Fluvial sands host excellent oil and gas reservoirs in various fields throughout the world. However, the lateral heterogeneity of reservoir properties within these reservoirs can be significant and determining the distribution of good reservoirs is a challenge. This study attempts to predict sand distribution within fluvial depositional systems by applying the Continuous Wavelet Transformation technique of spectral decomposition along with full spectrum seismic attributes, to a 3D seismic data set in the Pattani Basin, Gulf of Thailand. Full spectrum seismic attributes such as root mean square and coherency help to effectively map fluvial systems down to certain depth below which imaging is difficult in the intervals of interest in this study. However, continuous wavelet transform used in conjunction with other attributes by applying visualization techniques of transparency and RGB can be used at greater depths to extract from 3D seismic data useful information of fluvial depositional elements. This workflow may help to identify different reservoir compartments within the fluvial systems of the Gulf of Thailand.     

Continuous wavelet transforms of spectral decomposition analyses for fluvial reservoir characterization of Miano Gas Field,Indus Platform,Pakistan

Fluvial depositional systems constitute diverse host for the hydrocarbons all over the globe. Nevertheless, predicting the hydrocarbon sands within these assorted sand systems is a challenge for the prospect generation. We apply the continuous wavelet transform of spectral decomposition technique to a 3D seismic data of the Miano Gas Field in the Indus Platform, Pakistan. Full spectrum seismic attributes like the amplitude and root mean square (RMS) detect the reservoir sands down to a restricted reservoir compartment. Nonetheless, the continuous wavelet transforms can be advantageous in imaging and enactment of these clastic reservoirs within the whole reservoir zone. Rock physics reveal high-quality reservoir with an average porosity ～25% together with the discrimination of lithology/fluids, signifying the bright chances for ascertaining the potential stratigraphic reservoirs.     

Porosity prediction of lower cretaceous unconventional resource play,south Indus Basin,Pakistan, using the seismic spectral decomposition technique

Incised-valley shale systems are renowned as the fruitful exploration domains. However, the stratigraphic heterogeneity is significant, and thus, identifying the porous compartments within the thin-bedded and fractured shale system is one of the unconventional stratigraphic challenges. We present an innovative scheme for the exploration of the porous unconventional resources within the south Indus basin, Pakistan. The continuous wavelet transforms (CWT) exclusively detects the porous shales within the complete fractured system as compared to the full spectrum seismic data interpretation tool. The seismic amplitude, instantaneous frequency, and reflection strength tools show some tuning effects due to lithology and fluids. However, the tuning block of 28 Hz envelope sub-bands in conjunction with instantaneous phase tool accurately mark out the shale-plugged pinch out reservoirs. The synthetic wedge model based on the conventional seismic wavelet resolves the shale bed (incised-valley shale-filled lens) of about 23 m thickness, but shows limited imaging capability due to frequency band limitation for the porous shale locale. The acoustic impedance based on instantaneous spectral porosity modeling using the tuning volume of 28 Hz CWT has spectacularly resolved the thin-beds (gas shows) within the porosity range of 20 to 30%, which may have implications for future exploration of unconventional stratigraphic plays.     

Comparison of DSHA-based response spectrum with design response spectrum of building code of Pakistan (BCP-SP-2007) for a site in Muzaffargarh area,Pakistan

The building code of any country is considered to be a basic technical guidance document for the seismic design of structures. However, building codes are typically developed for the whole country, without considering site specific models that incorporate detailed site-specific data. Therefore, the adequacy of the design spectrum for building codes may sometimes be questionable. To study the sufficiency of the building codes of Pakistan (BCP-SP-2007), a deterministic seismic hazard analysis (DSHA) based spectrum was developed for a site in the Muzaffargarh area, Pakistan, using an updated earthquake catalogue, seismic source model, and a next generation attenuation model (NGA-WEST-2). Further, an International Building Code (IBC-2000) spectrum was developed for the study area to compare the results. The DSHA-based response spectrum resulted in a peak ground acceleration (PGA) value of 0.21 g for the Chaudwan fault. The evaluation of BCP-SP-2007 and IBC-2000 spectra provided a critical assessment for analyzing the associated margins. A comparison with the DSHA-based response spectrum showed that the BCP-SP-2007 design spectrum mostly overlapped with the DSHA spectrum unlike IBC-2000. However, special attention is needed for designing buildings in the study area when considering earthquake periods longer than 1 s, and the BCP-SP-2007 spectrum can be enhanced when considering a period range of 0.12–0.64 s. Finally, BCP-SP-2007 is based on a probabilistic approach and its comparison with deterministic results showed the significance of both methods in terms of design.