Effect of dynamic threshold pressure gradient on production performance in water-bearing tight gas reservoir

AbstractWater content and distribution have important impacts on gas production in water-bearing tight gas reservoirs. However, due to the structural and chemical heterogeneity of tight reservoirs, the water phase exists in various states, which has complicated the analyses of the effects of water characteristics on tight gas production performance. In this work, the water phase is distinguished from immobile to mobile states and the term of constrained water saturation is proposed. It is established that water can flow when the driving pressure difference is larger than the critical driving pressure difference. A new theoretical model of threshold pressure gradient is derived to incorporate the influences of constrained water saturation and permeability. On this basis, a new prediction model considering the varied threshold pressure gradient is obtained, and the result indicates that when threshold pressure gradient is constant, the real gas production capacity of the reservoir will be weakened. Meanwhile, a dynamic supply boundary model is presented, which indicates that the permeability has a strong influence on the dynamic supply boundary, whereas the impact of initial water saturation is negligible. These findings provide insights into the understanding of the effects of water state and saturation on the threshold pressure gradient and gas production rate in tight gas reservoirs. Furthermore, this study provides useful guidance on the prediction of field-scale gas production.Cited as: Zhu, W., Liu, Y., Shi, Y., Zou, G., Zhang, Q., Kong, D. Effect of dynamic threshold pressure gradient on production performance in water-bearing tight gas reservoir. Advances in Geo-Energy Research, 2022, 6(4): 286-295. https://doi.org/10.46690/ager.2022.04.0

Packed, Printable, and Polymorphic Return-Oriented Programming

Abstract. Return-oriented programming (ROP) is an attack that has been shown to be able to circumvent W ⊕ X protection. However, it was not clear if ROP can be made as powerful as non-ROP malicious code in other aspects, e.g., be packed to make static analysis difficult, be printable to evade non-ASCII filtering, be polymorphic to evade signaturebased detection, etc. Research in these potential advances in ROP is important in designing counter-measures. In this paper, we show that ROP code could be packed, printable, and polymorphic. We demonstrate this by proposing a packer that produces printable and polymorphic ROP code. It works on virtually any unpacked ROP code and produces packed code that is self-contained. We implement our packer and demonstrate that it works on both Windows XP and Windows 7 platforms. keywords: Return-oriented programming, packer, printable shellcode, polymorphic malware

Role of NAD(P)H Oxidase in Superoxide Generation and Endothelial Dysfunction in Goto-Kakizaki (GK) Rats as a Model of Nonobese NIDDM

Background: Cardiovascular disease is the leading cause of mortality in diabetics, and it has a complex etiology that operates on several levels. Endothelial dysfunction and increased generation of reactive oxygen species are believed to be an underlying cause of vascular dysfunction and coronary artery disease in diabetes. This impairment is likely the result of decreased bioavailability of nitric oxide (NO) within the vasculature. However, it is unclear whether hyperglycemia per se stimulates NADPH oxidase-derived superoxide generation in vascular tissue. Methods and Results: This study focused on whether NADPH oxidase-derived superoxide is elevated in vasculature tissue evoking endothelial/smooth muscle dysfunction in the hyperglycemic (16964 mg%) Goto-Kakizaki (GK) rat. By dihydroethidine fluorescence staining, we determined that aorta superoxide levels were significantly elevated in 9 month-old GK compared with age matched Wistar (GK; 19566%, Wistar; 10063.5%). Consistent with these findings, 10 26 mol/L acetylcholine-induced relaxation of the carotid artery was significantly reduced in GK rats compared with age matched Wistar (GK; 4167%, Wistar; 10065%) and measurements in the aorta showed a similar trend (p =.08). In contrast, relaxation to the NO donor SNAP was unaltered in GK compared to Wistar. Endothelial dysfunction was reversed by lowering of superoxide with apocynin, a specific Nox inhibitor. Conclusions: The major findings from this study are that chronic hyperglycemia induces significant vascular dysfunction i

deRop: Removing Return-Oriented Programming from Malware

Over the last few years, malware analysis has been one of the hottest areas in security research. Many techniques and tools have been developed to assist in automatic analysis of malware. This ranges from basic tools like disassemblers and decompilers, to static and dynamic tools that analyze malware behaviors, to automatic malware clustering and classification techniques, to virtualization technologies to assist malware analysis, to signature- and anomaly-based malware detection, and many others. However, most of these techniques and tools would not work on new attacking techniques, e.g., attacks that use return-oriented programming (ROP). In this paper, we look into the possibility of enabling existing defense technologies designed for normal malware to cope with malware using return-oriented programming. We discuss difficulties in removing ROP from malware, and design and implement an automatic converter, called deRop, that converts an ROP exploit into shellcode that is semantically equivalent with the original ROP exploit but does not use ROP, which could then be analyzed by existing malware defense technologies. We apply deRop on four real ROP malwares and demonstrate success in using deRop for the automatic conversion. We further discuss applicability and limitations of deRop. Copyright 2011 ACM.EI

Quasi-monoenergetic carbon ions generation from a double-layer target driven by extreme laser pulses

High quality energetic carbon ions produced via laser-plasma have many applications in tumor therapy, fast ignition and warm dense matter generation. However, the beam achieved in current experiments is still limited by either a large energy spread or a low peak energy. In this paper, a hybrid scheme for the generation of quasi-monoenergetic carbon ions is proposed by an ultra-intense laser pulse irradiating a double-layer target. Multi-dimensional particle-in-cell (PIC) simulations show that the carbon ions are first accelerated via laser piston mechanism in the former carbon layer and then further accelerated by Coulomb repulsion force in the attached neon target. Since electrons are bunched synchronously in longitudinal and transverse direction by radiation reaction during the whole acceleration process, a quasi-monoenergetic carbon ion beam is eventually produced. In the following stage, the neon target provides the Coulomb field required for the continuous acceleration of the carbon ions which helps to prevent the carbon ion layer from diffusion. It is demonstrated that quasi-monoenergetic carbon ions with peak energy of 465 MeV u ^−1 , energy spread of ∼13%, a divergence of ∼15 ^∘ , and laser-to-ion energy conversion of 20% can be achieved by using a laser pulse with intensity of 1.23 × 10 ^23 W cm ^−2 . An analytical model is also proposed to interpret the carbon ion acceleration, which is fairly consistent with the PIC simulations

Twisted radiation from nonlinear Thomson scattering with arbitrary incident angle

Thomson/Compton scattering is well-known as a scattering process between electromagnetic radiation and charged particles, which is found in laboratories and nature. Here, we investigate the radiative properties of nonlinear Thomson scattering with arbitrary incident angle. Based on classical electrodynamics, the analytical universal expressions of the electric field and energy spectrum of the radiation emitted by a relativistic electron scattering of circularly polarized laser field are derived. It is shown that the spatial distributions of the radiation energy of high-order harmonics have annular shapes and the symmetry of the annular shapes is strongly affected by the incident angle, which may relate with the angular momentum of twisted high-order harmonics. These results would help the understanding of the properties of twisted γ/X-ray and high energy electron-laser scattering experiments in laboratory

Echinacoside Induces Apoptosis in Human SW480 Colorectal Cancer Cells by Induction of Oxidative DNA Damages

Echinacoside is a natural compound with potent reactive oxygen species (ROS)-scavenging and anti-oxidative bioactivities, which protect cells from oxidative damages. As cancer cells are often under intense oxidative stress, we therefore tested if Echinacoside treatment would promote cancer development. Surprisingly, we found that Echinacoside significantly inhibited the growth and proliferation of a panel of cancer cell lines. Treatment of the human SW480 cancer cells with Echinacoside resulted in marked apoptosis and cell cycle arrest, together with a significant increase in active caspase 3 and cleaved PARP, and upregulation of the G1/S-CDK blocker CDKN1B (p21). Interestingly, immunocytochemistry examination of drug-treated cancer cells revealed that Echinacoside caused a significant increase of intracellular oxidized guanine, 8-oxoG, and dramatic upregulation of the double-strand DNA break (DSB)-binding protein 53BP1, suggesting that Echinacoside induced cell cycle arrest and apoptosis in SW480 cancer cells via induction of oxidative DNA damages. These results establish Echinacoside as a novel chemical scaffold for development of anticancer drugs

Betatron radiation polarization control by using an off-axis ionization injection in a laser wakefield acceleration

Tunable X-ray sources from a laser-driven wakefield have wide applications. However, due to the difficulty of electron dynamics control, currently the tunability of laser wakefield-based X-ray sources is still difficult. By using three-dimensional particle-in-cell simulations, we propose a scheme to realize controllable electron dynamics and X-ray radiation. In the scheme, a long wavelength drive pulse excites a plasma wake and an off-axis laser pulse with a short wavelength co-propagates with the drive pulse and ionizes the K-shell electrons of the background high-Z gas. The electrons can be injected in the wakefield with controllable transverse positions and residual momenta. These injected electrons experience controllable oscillations in the wake, leading to tunable radiations both in intensity and polarization

Efficient bright γ-ray vortex emission from a laser-illuminated light-fan-in-channel target

X/ γ -ray have many potential applications in laboratory astrophysics and particle physics. Although several methods have been proposed for generating electron, positron and X/ γ -photon beams with angular momentum (AM), the generation of an ultra-intense brilliant γ -ray is still challenging. Here, we present an all-optical scheme to generate a high energy γ -photon beam with large beam angular momentum (BAM), small divergence, and high brilliance. In the first stage, a circularly-polarized laser pulse with intensity of W/cm irradiates a micro-channel target, drags out electrons from the channel wall and accelerates them to high energies via the longitudinal electric fields. During the process, the laser transfers its spin angular momentum (SAM) to the electrons' orbital angular momentum (OAM). In the second stage, the drive pulse is reflected by the attached fan-foil and a vortex laser pulse is thus formed. In the third stage, the energetic electrons collide head-on with the reflected vortex pulse and transfer their AM to the -photons via nonlinear Compton scattering. Three-dimensional particle-in-cell simulations show that the peak brilliance of the γ -ray beam is ~ 10 22 photons/s/mm2/mrad2 /0.1% BW at 1 MeV with a peak instantaneous power of 25 TW and averaged BAM of 10δћ /photon. The angular momentum conversion efficiency from laser to the γ -photons is unprecedentedly 0.6

Spatial distribution of soil quality under different vegetation types in the Yellow River Delta wetland

The soils from four typical natural wetlands, namely, Phragmites australis, Tamarix chinensis, Suaeda salsa, and tidal flat, as well as reclaimed wetland, were selected to evaluate the soil quality in the Yellow River Delta. Fourteen soil physicochemical property indexes were employed to build a minimum data set (MDS). Combined with vegetation type and soil depth, the soil quality index (SQI) was conducted. A fuzzy logic model was applied for data normalization. The contrast test was conducted to verify the accuracy of the MDS. The results showed that the MDS consists of TOC, NO3--N, soil salinity, TS, TP, Mg, C/N and pH. The soil quality decreased from the inland to the coastline and from reclaimed wetland to tidal flat with the change of vegetation type. The soil quality of 0-10 cm soil depth was better than that of 20-30 cm soil depth. The soil qualities of reclaimed land were significantly better than those of natural wetlands at the same soil depth. Correlation analysis results showed that agricultural reclamation has become an important factor of soil quality change in the study area. Comparative results of two methods of MDS and the total data set (TDS) testified that the method of MDS was credible and accurate for soil quality assessment of the study area. Our results indicated that wetland protection and agricultural reclamation in coastal areas should keep a rational balance