TOC interpretation of lithofacies-based categorical regression model: A case study of the Yanchang formation shale in the Ordos basin, NW China

In this paper, taking the shale of Chang 7-Chang 9 oil formation in Yanchang Formation in the southeastern Ordos Basin as an example, through the study of shale heterogeneity characteristics, starting from the preprocessing of supervision data set, a logging interpretation method of total organic carbon content (TOC) on the lithofacies-based Categorical regression model (LBCRM) is proposed. It is show that: 1) Based on core observation, and Differences of sedimentation and structure, five lithofacies developed in the Yanchang Formation: shale shale facies, siltstone/ultrafine sandstone facies, tuff facies, argillaceous shale facies with silty lamina and argillaceous shale facies with tuff lamina. 2) The strong heterogeneity of shale makes it difficult to accurately explain the TOC distribution of shale intervals in the application of model-based interpretation methods. The LBCRM interpretation method based on the understanding of shale heterogeneity can effectively reduce the influence of formation factors other than TOC on the prediction accuracy by studying the characteristics of shale heterogeneity and constructing a TOC interpretation model for each lithofacies category. At the same time, the degree of unbalanced distribution of data is reduced, so that the data mining algorithm achieves better prediction effect. 3) The interpretability of lithofacies logging ensures the wellsite application based on the classification and regression model of lithofacies. Compared with the traditional homogeneous regression model, the prediction performance has been greatly improved, TOC segment prediction is more accurate. 4) The LBCRM method based on shale heterogeneity can better understand the reasons for the deviation of the traditional model-based interpretation method. After being combined with the latter, it can make logging data provide more useful information

Prefixed-threshold real-time selection for free-space phase-matching quantum key distribution

Phase-matching quantum key distribution (PM-QKD), a practical version of twin-field quantum key distribution (TF-QKD), is able to surpass the linear bound without quantum repeaters. Implementing PM-QKD through free space can guarantee two parties to share unconditionally secure keys between ground stations and mobile platforms. However, atmospheric turbulence (AT) in the free-space channel would decrease the secure key rate (SKR) since it would cause fluctuations of transmittances. Two works we do are presented in this paper. First, for simplicity and generality, we derive the SKR for 4-intensity PM-QKD with asymmetric channel transmittances. Secondly, we apply the observable model of the prefixed-threshold real-time selection (P-RTS) method to mitigate the effect of AT in PM-QKD. Here, the authorized parties predetermine the threshold of transmittances and use it to select the signals while monitoring the real-time transmittances. The results show that the performance of PM-QKD in free space is severely degraded by AT, while P-RTS can reduce the impact of AT, making it transmit more than 3 times as long the distance and have a 3.37 times as large SKR at a distance of 50 km

Sending-or-Not-Sending Twin-Field Quantum Key Distribution with a Passive Decoy-State Method

Twin-field quantum key distribution (TF-QKD) has attracted considerable attention because it can exceed the basic rate-distance limit without quantum repeaters. Its variant protocol, sending or not-sending quantum key distribution (SNS-QKD), not only fixes the security vulnerability of TF-QKD, but also can tolerate large misalignment errors. However, the current SNS-QKD protocol is based on the active decoy-state method, which may lead to side channel information leakage when multiple light intensities are modulated in practice. In this work, we propose a passive decoy-state SNS-QKD protocol to further enhance the security of SNS-QKD. Numerical simulation results show that the protocol not only improves the security in source, but also retains the advantages of tolerating large misalignment errors. Therefore, it may provide further guidance for the practical application of SNS-QKD

Prefixed-Threshold Real-Time Selection for Free-Space Sending-or-Not Twin-Field Quantum Key Distribution

As a variant of the twin-field quantum key distribution (TF-QKD), the sending-or-not twin-field quantum key distribution (SNS TF-QKD) is famous for its higher tolerance of misalignment error, in addition to the capacity of surpassing the rate–distance limit. Importantly, the free-space SNS TF-QKD will guarantee the security of the communications between mobile parties. In the paper, we first discuss the influence of atmospheric turbulence (AT) on the channel transmittance characterized by the probability distribution of the transmission coefficient (PDTC). Then, we present a method called prefixed-threshold real-time selection (P-RTS) to mitigate the interference of AT on the free-space SNS TF-QKD. The simulations of the free-space SNS TF-QKD with and without P-RTS are both given for comparison. The results showed that it is possible to share the secure key by using the free-space SNS TF-QKD. Simultaneously, the P-RTS method can make the free-space SNS TF-QKD achieve better and more stable performance at a short distance

Overweight and obesity are associated with cardiac adverse structure remodeling in Chinese elderly with hypertension

There is limited information on the association of overweight and obesity with cardiac remodeling in elderly population. Therefore, we investigated whether overweight and obesity are associated with cardiac geometric structures and function in Chinese elderly. A total of 1183 hospitalized patients (aged 65–99 years) with primary hypertension were collected retrospectively in a cross-sectional study, and divided into underweight, normal weight, overweight and obesity patient groups according to their body mass index (BMI). Cardiac echocardiographic parameters were compared between the groups. BMI was 17.2 ± 1.2, 21.4 ± 1.2, 25.1 ± 1.2, 30.2 ± 2.6 kg/m2 in underweight, normal weight, overweight and obesity groups respectively. Aortic and left atrial diameter, interventricular septal and left ventricular (LV) posterior wall thickness, LV end-diastolic and end-systolic diameter, and indexed LV mass, and prevalence of E/A reversal were higher, while LV ejection fraction and fractional shortening were lower in elderly with overweight or obesity, as compared with whose with underweight or normal weight separately (All P < 0.05). However, multivariable regression analysis showed that overweight and obesity are independently related to increased LV wall thickness, end-diastolic diameter and mass (All P < 0.05). In conclusions, this study demonstrates that overweight and obesity are associated with increased LV wall thickness, end-diastolic diameter and mass in Asian elderly.peerReviewe

Effect of counterions on comb-like polycarboxylate conformation in aqueous solutions

<p>Laser light scattering (LLS) and conductivity experiments were performed to investigate the effect of counterions on the conformation of polycarboxylate comb-like copolymers (PCEs) in aqueous solutions. The addition of monovalent ions (i.e., Na⁺ and K⁺) to dilute polycarboxylate comb-like copolymer solutions induced a slight shrinking of the molecular chains because of the screening of electrostatic intramolecular repulsion. Varying complexation phenomena, such as the formation of intramolecular complexation at certain Ca²⁺ concentrations and a transition between intermolecular and intramolecular complexations at different Ca²⁺ concentrations, were closely associated with Ca²⁺ concentration. Therefore, Ca²⁺ exerted a more complex influence on the conformation of PCEs with side chains containing polyethylene oxide (PEO) with different grafting densities. In addition, various combination types of Ca²⁺ with carboxylic groups were confirmed by theoretical simulation.</p