Double Cycle Research Articles

Exergo-economic and exergo-environmental evaluations and multi-objective optimization of a novel multi-generation plant powered by geothermal energy

An innovative multi-generation energy system is proposed to generate simultaneous power, drinking water, cooling, heating, and H2. The aimed plant comprised of an absorption chiller, a heat pump unit, a reverse osmoses unit, a double flash cycle, and a proton exchange membrane. The devised system is surveyed comprehensively based on the thermodynamic, thermo-economic, and exergoenvironmental indicators for offering an in-depth assessment of the plant. Besides, multi-objective optimization has been employed in the proposed system. The net proportions of output work, unit cost, thermal and exergetic efficiencies, and H2, and purified water production of the system are 99.25 kW, 124 $/GJ, 24.4%, 32.1%, 1.218 kg/h, and 0.9662 kg/s, separately. The outcomes related to thermodynamic and thermo-economic evaluations demonstrate that the greatest amount of total cost rate occurred in the first employed turbine. Owing to the findings of the parametric study, by increasing geothermal temperature, exergoenvironmental parameters are reduced, and with increasing the pressure of FT1, cooling load and energetic efficiency increase while SUCP, net output work, and exergetic efficiency decrease dramatically.

Using waste energy of double-effect refrigeration cycle to produce potable water: Energy and economic analysis

Regarding the crisis of energy and potable water (PW) in addition to the emergence of many environmental problems due to the use of fossil fuels, it is necessary to utilize the waste energy of industrial equipment to produce PW without using another source of energy. The double effect refrigeration cycle (DERC) is known as one the popular industrial equipment which has valuable waste heat at a notable temperature. In this study, the mentioned waste energy is used as an independent source of energy to produce PW in thermal desalination systems. According to the various types of thermal desalination systems capable of using the waste heat, four thermal desalination systems including single effect evaporation (SEE), triple effect evaporation (TEE), single effect adsorption vapor compression (SEAdVC), and single effect thermal vapor compression (SETVC) are considered and compared comprehensively from the perspective of energy and economic. Using the integrated systems, it is possible to produce 8.7–46.9 m3/day of PW and 5.6 MWh/day of cooling; in addition to enhancing the energy efficiency of the system by 10.6–57%. To select the best desalination method in combination with DERC, the methods are compared according to a scoring method by using the AHP (Analytic Hierarchy Process) weight factors for the various scenarios with different priorities. The TEE method is the best option in a scenario where the produced PW is the main priority. Nevertheless, if all considered criteria have the same weight factor, SETVC has the highest score.

A nested bistable module within a negative feedback loop ensures different types of oscillations in signaling systems

In this article, we consider a double phosphorylation cycle, a ubiquitous signaling component, having the ability to display bistability, a behavior strongly related to the existence of positive feedback loops. If this component is connected to other signaling elements, it very likely undergoes some sort of protein–protein interaction. In several cases, these interactions result in a non-explicit negative feedback effect, leading to interlinked positive and negative feedbacks. This combination was studied in the literature as a way to generate relaxation-type oscillations. Here, we show that the two feedbacks together ensure two types of oscillations, the relaxation-type ones and a smoother type of oscillations functioning in a very narrow range of frequencies, in such a way that outside that range, the amplitude of the oscillations is severely compromised. Even more, we show that the two feedbacks are essential for both oscillatory types to emerge, and it is their hierarchy what determines the type of oscillation at work. We used bifurcation analyses and amplitude vs. frequency curves to characterize and classify the oscillations. We also applied the same ideas to another simple model, with the goal of generalizing what we learned from signaling models. The results obtained display the wealth of oscillatory dynamics that exists in a system with a bistable module nested within a negative feedback loop, showing how to transition between different types of oscillations and other dynamical behaviors such as excitability. Our work provides a framework for the study of other oscillatory systems based on bistable modules, from simple two-component models to more complex examples like the MAPK cascade and experimental cases like cell cycle oscillators.

The technological innovation effect of industrial chain under the 'double cycle' pattern in the post epidemic era

In order to improve the economic benefits of enterprises under continuing influence of COVID-19, the technological innovation effect of industrial chain under the 'double cycle' pattern in the post epidemic era is studied in this paper. The fractional planning and integral planning functions of the industrial chain are obtained by constructing the CCR model, and the BCC model calculation of the innovation effect of the enterprise industrial chain is realised by the Chames-Cooper transformation. The data efficiency value of technological innovation effect of industrial chain under the 'double cycle' pattern is obtained via the SBM network model for analysis on the technological innovation effect of industrial chain. The experimental results show that the effect of industrial chain technological innovation is analysed from the aspects of main business income and the profit margin of enterprises extending the industrial chain and connecting the industrial chain. The highest profit margin after connecting the industrial chain technological innovation is 34.2%, which proves that technological innovation can improve the economic benefits of enterprises.

The technological innovation effect of industrial chain under the 'double cycle' pattern in the post epidemic era

The technological innovation effect of industrial chain under the 'double cycle' pattern in the post epidemic era

Effect of an Internal Heat Exchanger on the Performances of a Double Evaporator Ejector Refrigeration Cycle

A theoretical investigation is presented about a double evaporator ejector refrigeration cycle (DEERC). Special attention is paid to take into account the influence of the sub-cooling and superheating effects induced by an internal heat exchanger (IHX). The ejector is introduced into the baseline cycle in order to mitigate the throttling process losses and increase the compressor suction pressure. Moreover, the IHX has the structure of a concentric counter-flow type heat exchanger and is intentionally used to ensure that the fluid at the compressor inlet is vapor. To assess accurately the influence of the IHX on the DEERC performance, a mathematical model is derived in the frame of the dominant one-dimensional theory for ejectors. The model also accounts for the friction effect in the ejector mixing section. The equations of this model are solved using an Engineering Equation Solver (EES) for different fluids. These are: R134a as baseline fluid and other environment friendly refrigerants used for comparison, namely, R1234yf, R1234ze, R600, R600a, R290, R717 and R1270. The simulation results show that the DEERC with an IHX can achieve COP (the coefficient of performance) improvements from 5.2 until 10%.

Solvation rules: aromatic interactions outcompete cation-π interactions in synthetic host-guest complexes in water.

Chemical double mutant cycles were used to measure the interaction of a N-methyl pyridinium cation with a π-box in a calix[4]pyrrole receptor. Although the cation-π interaction is attractive (-11 kJ mol-1), it is 7 kJ mol-1 less favourable than the corresponding aromatic interaction with the isosteric but uncharged tolyl group.

Aromatic interactions with heterocycles in water.

Conformationally well-defined supramolecular complexes that can be studied in different solvents provide a platform for separating and quantifying free energy contributions due to functional group interactions and desolvation. Here 1:1 complexes formed between four different calix[4]pyrrole receptors and eleven different pyridine N-oxide guests have been used to dissect the factors that govern aromatic interactions with heterocycles in water and in chloroform solution. 1H NMR spectroscopy shows that the three-dimensional structures of the complexes are fixed by four H-bonding interactions between the pyrrole donors at the bottom of the receptor and the N-oxide acceptor on the guest, locking the geometrical arrangement of interacting functional groups in the binding pocket at the other end of the receptor. An aromatic heterocycle on the guest makes two stacking interactions and two edge-to-face interactions with the side walls of the receptor. Chemical double mutant cycles were used to measure the free energy contribution of these four aromatic interactions to the overall stability of the complex. In chloroform, the aromatic interactions measured with pyridine, pyrimidine, furan, thiophene and thiazole are similar to the interactions with a phenyl group, but the effect of introducing a heteroatom depends on where it sits with respect to the aromatic side-walls of the cavity. A nitrogen lone pair directed into a π-face of the side-walls of the binding site leads to repulsive interactions of up to 8 kJ mol-1. In water, the heterocycle aromatic interactions are all significantly more favourable (by up to 12 kJ mol-1). For the non-polar heterocycles, furan and thiophene, the increase in interaction energy correlates directly with hydrophobicity, as measured by the free energy of transfer of the heterocycle from n-hexadecane into water (ΔG°(water-hex)). For the heterocycles with polar nitrogen H-bond acceptors, water can access cracks in the walls of the receptor binding site to solvate the edges of the heterocycles without significantly affecting the geometry of the aromatic interactions, and these nitrogen-water H-bonds stabilise the complexes by about 15 kJ mol-1. The results highlight the complexity of the solvation processes that govern molecular recognition in water.

Substituent effects on aromatic interactions in water.

Molecular recognition in water involves contributions due to polar functional group interactions, partial desolvation of polar and non-polar surfaces and changes in conformational flexibility, presenting a challenge for rational design and interpretation of supramolecular behaviour. Conformationally well-defined supramolecular complexes that can be studied in both water and non-polar solvents provide a platform for disentangling these contributions. Here 1 : 1 complexes formed between four different calix[4]pyrrole receptors and thirteen different pyridine N-oxide guests have been used to dissect the factors that govern substituent effects on aromatic interactions in water. H-bonding interactions between the receptor pyrrole donors and the guest N-oxide acceptor at one end of the complex lock the geometrical arrangement of a cluster of aromatic interactions at the other end of the complex, so that a phenyl group on the guest makes two edge-to-face and two stacking interactions with the four aromatic side-walls of the receptor. The thermodynamic contribution of these aromatic interactions to the overall stability of the complex was quantified by chemical double mutant cycles using isothermal titration calorimetry and 1H NMR competition experiments. Aromatic interactions between the receptor and a phenyl group on the guest stabilise the complex by a factor of 1000, and addition of substituents to the guest phenyl group further stabilises the complex by an additional factor of up to 1000. When a nitro substituent is present on the guest phenyl group, the complex has a sub-picomolar dissociation constant (370 fM). The remarkable substituent effects observed in water for these complexes can be rationalised by comparison with the magnitude of the corresponding substituent effects measured in chloroform. In chloroform, the double mutant cycle free energy measurements of the aromatic interactions correlate well with the substituent Hammett parameters. Electron-withdrawing substituents increase the strength of the interactions by a factor of up to 20, highlighting the role of electrostatics in stabilising both the edge-to-face and stacking interactions. The enhanced substituent effects observed in water are due to entropic contributions associated with the desolvation of hydrophobic surfaces on the substituents. The flexible alkyl chains that line the open end of the binding site assist the desolvation of the non-polar π-surfaces of polar substituents, like nitro, but at the same time allow water to interact with the polar H-bond acceptor sites on the substituent. This flexibility allows polar substituents to maximise non-polar interactions with the receptor and polar interactions with the solvent, leading to remarkably high binding affinities.

Ir(IV) and Ir(III) in situ transition promotes ROS generation for eradicating multidrug-resistant bacterial infection.

Whether reactive oxygen species are a consequence or a cause of antibacterial activity is not fully known. A glutathione (GSH)-mediated oxidative defense mechanism is an important factor against bacterial infection. Reactive oxygen species (ROS) storm-mediated bacterial death by depleting GSH is also considered an effective strategy. Therefore, we designed and synthesized hybrid iridium ruthenium oxide nanozymes (IrRuOx NPs), where IrRuOx NPs alternately consume GSH through double redox electron pair auto-valent cycles, while an IrRuOx NP-mediated Fenton-like reaction occurs to realize an ROS storm, which in turn mediates lipid peroxidation to promote bacterial death. The results showed that IrRuOx NPs can effectively inhibit and kill Gram-positive and Gram-negative bacteria in vitro, and can be used as broad-spectrum antibiotics. Importantly, the wound and sepsis models of MRSA infection confirmed the efficient antibacterial activity of IrRuOx NPs in vivo. Accordingly, this study provides a new idea for metal oxide hybrid nanoenzymes and their biological functions.

Smooth Compactifications of the Abel-Jacobi Section

Abstract For $\theta $ a small generic universal stability condition of degree $0$ and A a vector of integers adding up to $-k(2g-2+n)$ , the spaces $\overline {\mathcal {M}}_{g,A}^\theta $ constructed in [AP21, HMP+22] are observed to lie inside the space $\textbf {Div}$ of [MW20], and their pullback under $\textbf {Rub} \to \textbf {Div}$ of loc. cit. to be smooth. This provides smooth and modular modifications $\widetilde {\mathcal {M}}_{g,A}^\theta $ of $\overline {\mathcal {M}}_{g,n}$ on which the logarithmic double ramification cycle can be calculated by several methods.

Measuring the Status of Jiangxi Aviation Industry Chain Nodes under the New Pattern of Double Cycle and Improving the Path

Measuring the Status of Jiangxi Aviation Industry Chain Nodes under the New Pattern of Double Cycle and Improving the Path

Supply chain integration, circulation industry development and unified large market---From the perspective of Internet popularization

The construction of a unified big market is the inevitable requirement of China’s continuous deepening of reform, which plays an important role in eliminating the urban-rural gap and promoting the domestic and international double cycle. The key to building a large, unified national market is to promote high-standard connectivity of market facilities, continue to deepen and popularize through the Internet, combine supply chain integration with the development of the circulation industry, reduce institutional transaction costs and explicit costs such as raw materials, labor and logistics, break local protection, curb market segmentation, and update infrastructure. In this way, market transaction costs can be reduced, scale advantages can be leveraged and resource allocation can be optimized.

The Application of Profit Media and Market Cognition in Asset Structure

China proposes to build a new development pattern with the domestic big cycle as the main body and the domestic and international double cycles promoting each other. In this context, domestic enterprises inevitably need operational transformation, especially the optimization and adjustment of their asset structure. Therefore, it requires domestic enterprise decision-makers to ponder how to optimize the asset structure in order to win in excess competition under the conditions of excess market. This issue constitutes the key to the implementation of the "dual cycle" new development pattern for enterprises. In this article, the market epistemic difference between asset reorganization and production structure optimization, and how the profit media parameters affect the market's consciousness of asset structure optimization. The summaries forecast that the exchanges identify the differences of asset structure between triumphant and unsuccessful companies, but without confirming them as valid value signals, nor can it distinguish whether the adjustment measures of asset structure targeted towards production optimization or value of profit, by studying the asset structure of enterprises is also of practical significance for improving the production and operation efficiency of enterprises.

SO3 Migration and Emission Characteristics of CFB Boilers

In order to study the migration and transformation of SO3 from circulating fluidized bed boiler (CFB) in the air preheater and flue gas treatment facilities, 10 circulating fluidized bed boilers with installed capacities between 150 MW and 330 MW were measured by controlled condensation method. Ten circulating fluidized bed boilers with installed capacities ranging from 150 MW to 330 MW were measured using the controlled condensation method. It is showed that the SO3 removal rate of the air preheater was affected by the air preheater flue gas exit temperature, which ranged from 6.7 % to 36.5 %, and the SO3 removal rate of the rotary air preheater was higher than that of the tubular air preheater. The SO3 removal rate of cloth bag filter and electric bag filter is above 40 %; the SO3 removal rate of electrostatic precipitator is between 6.1 % and 10.8 %. The SO3 removal rate of wet desulfurization method ranges from 41.7 % to 73.4 %, with the highest SO3 removal rate of double tower double cycle. The SO3 removal rate of off-furnace CFB semi-dry desulfurization reached 89.7 %~97.9 %, and the dry process inside the furnace + off-furnace CFB semi-dry process could reduce the SO3 at the desulfurization outlet to below 0.3 mg/m3 under the tested conditions. The conclusions of the test analysis in this paper can provide reference for SO3 control in circulating fluidized bed boilers and related policy formulation.

A Study on the Marketing Optimization Strategy of Exhibition Industry in Dalian under the "Dual Circulation" Development Paradigm

The Chinese government stressed the need to build a new development pattern with the domestic big cycle as the main body and the domestic and international double cycles promoting each other. As a convention and exhibition center city in Northeast Asia, Dalian’s exhibition industry has made brilliant achievements. However, in recent years, influenced by market competition, industrial policy adjustment and other factors, there are still some problems in the marketing strategy of Dalian exhibition industry, compared with the marketing strategy of exhibition industry in developed regions. Strengthening innovation leadership and optimizing marketing strategies will help promote industrial upgrading and transformation, and then improve the quality and efficiency of economic development. This study will provide reference value for the improvement and promotion of Dalian’s exhibition industry.

Research on Theoretical Mechanism and Promotion Path of Digital Economy Driving China's Green Development under "Double Carbon" Background.

(1) Background: Under the background of building a new pattern of "double cycle" development, the green meaning of the digital economy is highly valued. The innovative feature of the digital economy is forming a new economic growth pole, and gradually becomes the driving force for China's economic restructuring and green development; (2) methods: this paper empirically tests whether the digital economy can promote green development by using various econometric models based on panel dataset with 30 provinces from 2011 to 2019 in mainland China and measuring the development level of the digital economy and the greening index; (3) results: it is found that the digital economy can directly boost green development in greening degree of economic growth, resources and environment-carrying potential, and government policy support. The digital economy's influence on green development has an inverted U-shaped trend; environmental control is an effective regulatory variable with a substitution effect on green development. With an obvious regional heterogeneity, the digital economy promotes green development; the digital economy can greatly affect green growth through technical innovation through mechanism analysis. The robustness test supports the above conclusion; (4) conclusions: the findings provide a foundation for multi-party policymakers to effectively formulate and implement policies for the digital economy that encourage green growth.

Sperm DNA integrity does play a crucial role for embryo development after ICSI, notably when good-quality oocytes from young donors are used

Based on the inconsistent literature published thus far involving infertile patients, whether intracytoplasmic sperm injection (ICSI) allows overcoming total fertilization failure due to sperm DNA fragmentation is still unclear. Related to this, female factors, which may have a significant impact on assisted reproduction outcomes, can mask male infertility. In this scenario, evaluating ICSI outcomes following cycles using healthy donor gametes could shed light on this realm, as it would avoid the influence of (un)known confounding factors present in infertile individuals. The present work, therefore, aimed to address whether single- and double-stranded sperm DNA fragmentation leads to impaired ICSI outcomes in double gamete donation cycles. The study also compared these double-gamete donation cycles to cycles in which only sperm were donated and oocytes were obtained from infertile patients. Two cohorts were included: (a) the Donor-Donor (DD) cohort, which included 27 semen donor samples used in 49 ICSI cycles with young healthy oocyte donors; and (b) the Donor-Infertile (DI) cohort, which involved 34 semen donor samples used in 57 ICSI cycles with oocytes from patients. Single- and double-stranded sperm DNA breaks were determined with alkaline and neutral Comet assays, respectively; ICSI was conducted following standard protocols and embryos were monitored through time-lapse microscopy. In the DD cohort, the percentage of sperm with high overall DNA damage correlated with fertilization rates (Rs = − 0.666; P < 0.001) and with the percentage of blastocysts per injected oocyte (Rs = − 0.414; P = 0.040). In addition, sperm DNA damage delayed the first embryo division (Rs = 0.421; P = 0.036), and development from the 8-cell to the morula stage (Rs = 0.424; P = 0.034). In contrast, double-stranded DNA breaks had no effect in this cohort. As far as the DI cohort is concerned, while overall sperm DNA damage was not found to be correlated to fertilization or blastocyst rates, pronuclei formation following ICSI was delayed when the incidence of double-stranded DNA breaks was high (Rs = 0.485; P = 0.005). In conclusion, this study, which is the first involving double donation cycles (i.e., a donor-donor cohort), supports that sperm DNA damage has a detrimental impact on fertilization rates after ICSI, and delays embryo development. Moreover, the use of oocytes from infertile individuals is suggested to hide the male-factor effect.

Study on the Dynamic Evolution and Regional Differences of the Level of High-Quality Economic and Social Development in China

Analyzing the dynamic evolution and regional differences of the level of high-quality economic and social development based on the perspective of long time can be beneficial for informing the effect of the economy in China. This study builds a development evaluation index system oriented to high-quality economic and social development in five directions. To deepen the analysis, TOPSIS entropy is used to measure the level of economic and social development of 31 provinces in China from 2000 to 2019, considering the temporal characteristics and evolution laws of four regions. Dagum’s Gini coefficient method is also applied to measure regional differences and discover driving factors. There are three key results. First, the comprehensive development index runs well; however, the index of economic momentum, innovationability, and safety assurance differ significantly. There is obvious path dependence, demonstrating a spatial gradient, with development that is high in the east, moderate in the central part, and low in the west. Second, the trend of the comprehensive development index of each province is gratifying, but there are obvious differences in the three dimensions of economic momentum, innovation ability, and security index. Third, the overall development coordination of the four regions is weak—that is, the levels of economic and social development oriented to high-quality intensified differentiation; it will be difficult to close the regional gap in the short term, given the development heterogeneity among regions. To promote the formation of a new, balanced pattern of regional development of high quality with complementary advantages, the four regions should be targeted in a double cycle of implementing regional development strategies and enhancing development coordination. Attention should also be paid to the growth pole function of advanced regions, complementing the advantages of other regions, and ultimately promoting high-quality development jointly.

Efficient distributed concentrating solar power system with ammonia-based chemical heat pump

Recently, distributed renewable energy system has become a flexible, reliable and environmentally friendly alternative to the conventional large-scale centralized power plant. This paper proposed a distributed concentrating solar power system coupled with an ammonia-based chemical heat pump. The proposed system is able to upgrade the solar thermal energy absorbed from 450 °C to 650 °C. To design a concentrated solar module, consisting of a Linear Fresnel Reflector field and a Compound Parabolic Collector, for the proposed system, a three-dimensional optical model is developed with SolTrace software. Moreover, the optical model has been validated by comparing the model predicted results with the data from the reference. As for the ammonia decomposition membrane reactor in the system, a three-dimensional reactor model is developed with COMSOL software, which is capable of simulating both ammonia decomposition and hydrogen permeation processes under solar irradiation. With an experimental prototype of the membrane reactor, experiments have been conducted to validate the reactor model. With the validated model, the effects of the reactor length, reactor inlet temperature and ammonia flow rate on the thermochemical conversion efficiency of the reactor have been investigated parametrically. The results show that the reaction conversion increases with the reactor length increasing, while thermochemical conversion efficiency decreases. The thermochemical conversion efficiency increases with reactor inlet temperature and/or ammonia flow rate increasing, which reaches the maximum of 34.9 % in our study. By integrating an ultra-supercritical double reheat power cycle, the system with a low concentration ratio of ∼ 24 can achieve a high solar to power efficiency of ∼ 18.3 %, which surpasses the peak efficiency of a typical concentrating solar power plant with a concentration ratio of ∼ 30.