Small Cycle Research Articles

Symposium on chemistry of alkynes, allenes and small cycles

The symposium on the chemistry of alkynes, allenes and small cycles was held from July 3 to July 6, 2023 at St. Petersburg State University as part of the All-Russian conference with international participation “Ideas and legacy of A.E. Favorsky in organic chemistry”. Leading experts in the chemistry of alkynes, allenes and small cycles took part in the symposium; the latest achievements in the chemistry of these classes of compounds were presented and further development prospects were discussed. This review contains brief annotations of the reports and references to the corresponding publications of the authors.

A machine learning-based method for multi-satellite SAR data integration

Large- and small-scale subsidence coexist in the world's coastal cities due to extensive land reclamation and fast urbanization. Synthetic aperture radar (SAR) images are typically limited by either low resolution or small coverage, making them ineffective for fully monitoring displacement in coastal areas. In this research, a machine learning-based method is developed to investigate the reclaimed land subsidence based on multi-satellite SAR data integration. The proposed method requires at least a pair of SAR images from complementary tracks. First, the line-of-sight (LOS) displacements are recovered in connection to a series of extremely coherent points based on the differential interferometry synthetic aperture radar (DInSAR). These LOS displacements are then converted into their vertical component, geocoded to a common grid, and simultaneously integrated (i.e., pixel-by-pixel) based on Support Vector Regression (SVR). The proposed methodology does not necessitate the simultaneous processing of huge DInSAR interferogram sequences. The experiments include high-resolution COSMO-SkyMed (CSK) and TerraSAR-X (TSX) images, as well as a small monitoring cycle Sentinel-1 (S1) images of reclaimed territories near Hong Kong Kowloon City. The overall average annual displacement (AAD) ranges from -12.86 to 11.63 mm/year derived from 2008 to 2019. The evaluation metrics including RMSE, MAE, correlation coefficient, and R-squared are used to investigate the impact of SVR in the integration of SAR datasets. Based on these evaluation metrics, SVR is superior in terms of integration performance, accuracy, and generalization ability. Thus, the proposed method has potentially performed multi-satellite SAR data integration.

Multi-objective optimization application for a coupled light water small modular reactor-combined heat and power cycle (cogeneration) systems

The goal of this research is to propose a way to maximize small modular reactor (SMR) utilization to gain better market feasibility in support of carbon neutrality. For that purpose, a comprehensive tool was developed, combining off-design thermohydraulic models, economic objective models (levelized cost of electricity, annual profit), non-economic models (saved CO2), a parameter input sampling method (Latin hypercube sampling, LHS), and a multi-objective evolutionary algorithm (Non-dominated Sorting Algorithm-2, NSGA2 method) for optimizing a SMR-combined heat and power cycle (CHP) system design. Considering multiple objectives, it was shown that NSGA2+LHS method can find better optimal solution sets with similar computational costs compared to a conventional weighted sum (WS) method. Out of multiple multi-objective optimal design configurations for a 105 MWe design generation rating, a chosen reference SMR-CHP system resulted in its levelized cost of electricity (LCOE) below $60/MWh for various heat prices, showing economic competitiveness for energy market conditions similar to South Korea. Examined economic feasibility may vary significantly based on CHP heat prices, and extensive consideration of the regional heat market may be required for SMR-CHP regional optimization. Nonetheless, with reasonable heat market prices (e.g. district heating prices comparable to those in Europe and Korea), SMR can still become highly competitive in the energy market if coupled with a CHP system.

Li+ Conduction in a Polymer/Li1.5Al0.5Ge1.5(PO4)3 Solid Electrolyte and Li-Metal/Electrolyte Interface.

The solid oxide electrolyte Li1.5Al0.5Ge1.5(PO4)3 (LAGP) with a NASICON structure has a high bulk ionic conductivity of 10-4 S cm-1 at room temperature and good stability in the air because of the strong P5+-O2- covalence bonding. However, the Ge4+ ions in LAGP are quickly reduced to Ge3+ on contact with the metallic lithium anode, and the LAGP ceramic has insufficient physical contact with the electrodes in all-solid-state batteries, which limits the large-scale application of the LAGP electrolyte in all-solid-state Li-metal batteries. Here, we prepared flexible PEO/LiTFSI/LAGP composite electrolytes, and the introduction of LAGP as a ceramic filler in polymer electrolytes increases the total ionic conductivity and the electrochemical stability of the composite electrolyte. Moreover, the flexible polymer shows good contact with the electrodes, resulting in a small interfacial resistance and stable cycling of all-solid-state Li-metal batteries. The influence of the external pressure and temperature on Li+ transfer across the Li/electrolyte interface is also investigated.

Bursting oscillations in coupling Mathieu-van der Pol oscillator under parametric excitation

The bursting oscillation is a fast-slow oscillation. A complex four-dimensional coupled Mathieu-van der Pol oscillator is analyzed to investigate the bursting oscillations. The multiscale phenomena appear in four-dimensional coupled Mathieu-van der Pol oscillator due to the significant difference between the natural frequencies of the system and frequencies of the parametric excitation. Analyzing the bifurcation diagrams of four-dimensional coupled Mathieu-van der Pol oscillator using the bifurcation theory and fast-slow analysis, we identify four different bursting oscillation modes. Additionally, an intriguing phenomenon is observed as the parameters of the fast and slow systems change in the orbits. This phenomenon is called as the slow channel effect. The trajectory traverses the bifurcation point without the immediate bifurcation behaviors but gradually converges to a stable limit cycle after an apparent delay. Four-dimensional coupled Mathieu-van der Pol oscillator has a composite Hopf bifurcation which means that a Hopf bifurcation respectively corresponds to the large and small limit cycles. This research provides the insights into the mechanism of the bursting oscillations.

Public Perception of Green Supply Chains and Its Impact on Customer Behavior: An Empirical Analysis

The public is increasingly becoming aware of environmental challenges and adjusting its purchasing behavior in pursuit of sustainable products and services. To compete in the global scene, firms need to transform their supply chains to adhere to eco-friendly practices. This study focuses on the electronics market, which is distinctively interesting due to its small product life cycles, high-end capabilities, and fierce competition. A novel research model comprising nine hypotheses that attempt to investigate and assess the factors influencing customers’ perceptions and purchasing preferences in relation to green supply chains in the electronics industry was developed. We conducted field research to test the model empirically using survey data from 147 individuals with different backgrounds. The dataset was verified and validated by means of explanatory factor analysis. Structural equation modeling analysis was performed that revealed the linkage between demographics (age), willingness to pay, purchasing intention, and green consumerism. Other research findings included the intricate interconnections between environmental concern, knowledge, attitude, customers’ perceptions/effectiveness, and behavior. This research gives insights into green consumerism in the electronics sector, and its managerial implications can guide sustainable supply chain practices and customer-centric marketing approaches.

Numerical simulation and low speed experiment of a low partially admitted rate axial turbine for small scale organic Rankine cycle

High rotating speed is a prominent feature of turbine used for small-scale organic Rankine cycle (ORC) system, which can bring the problems of safety, reliability, sealing, vibration, economics, etc. Partial admission method has potential to reduce the rotating speed of small turbine. In this study, an axial turbine with low partially admitted rate of 0.033 was tested in ORC loop using R1233zde as working fluid, and numerically researched using Ansys CFX software with k-omega turbulence model. Results showed that the specific powers of turbine resulting from CFD should be corrected with losses to match well with the experimental results. Losses could reduce the optimal rotating speed of turbine. The optimal rotating speed, mass flow rate, power and efficiency of turbine under rated condition were 8000 RPM, 115.8 g/s, 611.8 W and 35.8 %, respectively. The corresponding power and thermal efficiency of ORC were 551.0 W and 2.15 %. The influences of inlet and back pressures on the performance of turbine were different. With constant inlet pressure and temperature, the mass flow rate kept almost unchanged after chocking, but the power continued to increase. Under allowable conditions, reducing back pressure of turbine played an important role in improving turbine performance.

Hidden in plain sight. Global heating, the small water cycle, and the social contract

ABSTRACT Greenhouse gases do not generate heat. Bare ground is the furnace: vegetation and the water cycle provide the air-conditioning. Heat is emitted as infrared radiation; greenhouse gases in the atmosphere absorb some of this outgoing radiation which then heats the atmosphere or is reabsorbed by the land and, mainly, the oceans. So, control of greenhouse gas emissions is necessary and urgent – but it will not be enough to arrest global heating and does nothing for the water cycle. Clearance of natural landscapes for agriculture has driven global heating and disrupted the water cycle. Regenerative agriculture combats these hazards by avoiding bare soil, not ploughing, adopting a diverse crop rotation including perennial grasses and legumes, and creating windbreaks and wetlands. Speedier uptake of these society-saving practices requires a new social contract. The war in Ukraine provides an opportunity as well as urgent need.

Characterization of elementary reactions inducing coal spontaneous combustion

Twenty-five reactions involving R⋅, ⋅OH, ⋅OOH, R–CH2OH, R–COOH, R–CHO, R–CH3, ROO⋅, R–CH2O⋅, R–C(=O)–O⋅, and R–Ċ=O reactive tissues were studied by computational chemistry to reveal the microscopic mechanism of coal spontaneous combustion (CSC). Results showed that R⋅ chemisorbed oxygen to form ROO⋅. Then, ROO⋅ captured the H atom from alkane or self-structure to generate ⋅OH and R⋅. Accordingly, a cyclic reaction centered on R⋅ was formed. In addition, the reaction of the reactive groups (R–CH3, R–CH2OH, R–COOH and R–CHO) with hydroxyl radicals, which requires low activation energy and is accompanied by exotherm, is the main pathway to produce R⋅, R–CH2O⋅, R–C(=O)–O⋅, and R–Ċ=O. Subsequently, condensation reactions occurred between ⋅OH and R⋅, ⋅OOH and R–Ċ–OH, R–CO⋅ and R⋅, and R–C(=O)–O⋅ and R⋅, which can spontaneously proceed and release large amounts of heat, accelerating the self-heating of the coal. O2 can directly capture the H atom on the alkyl group to generate R⋅ and ⋅OOH as the coal body temperature reaches 30 °C–70 °C.⋅OOH can also capture the H atoms on the alkyl group to generate R⋅. Consequently, another small cycle of radical reactions centered on R⋅ is formed. Meanwhile, the reactions of ⋅OOH and R⋅ with R–CH2OH, R–COOH, and R–CHO provide two additional pathways to generate R–CH2O⋅, R–C(=O)–O⋅, and R–Ċ=O. Finally, the decomposition reactions of R–CH2O⋅, R–C(=O)–O⋅ and R–Ċ=O are the main pathways to produce R⋅, CO2, and CO, respectively. Accordingly, a macrocycle chain reaction of free radicals is formed. Therefore, removal of ⋅OH, R⋅, ⋅OOH, and ROO⋅ is the key to break the chain reaction of the CSC cycle.

Enhanced quadratic DC–DC boost converters with super‐wide voltage gain ranges and ultra‐low voltage stress for renewable energy systems

AbstractAs the promising and ideal clean energies, wind and solar energy systems are in desperate need of high‐performance DC–DC converters to realize efficient and reliable energy transformation. Conventional DC–DC converters for renewable energy systems will work at extreme duty cycles and affect the system efficiency and reliability owing to their limited voltage gains and high‐voltage stress. In this paper, by adopting the hybrid voltage multiplier cells, two enhanced quadratic boost converters (EQBCs) which are highly desirable for renewable energy applications are proposed and analyzed. The EQBCs possess super‐wide voltage gain ranges and ultra‐low voltage stress; therefore, small duty cycle conditions can be achieved and components with low‐rated voltages can be chosen to decrease system volumes and increase system efficiencies. Besides, the EQBCs possess continuous input currents, which can realize small input current ripples and avoid the serious effect of pulsating current on the input sources. What's more, stable output voltages and simple controller circuits are realized by the EQBCs because of the common grounded structures of the input terminal, the single active switch and the output terminal. Detailed principle analyses, parameter designs, performance comparisons and experimental prototypes are conducted to verify the characteristics and feasibilities of the EQBCs.

Ultrasensitive quantitation of Paraquat based on a small molecule-induced dual-cycle amplification strategy

Paraquat (PQ) is a typical biotoxic small molecule. Knowledge of how to directly introduce it into cyclic amplification rather than transform it into a secondary target is lacking in current analytical methods. Considering the urgent need for trace pesticide residue detection and the inherent defects of small molecule analysis, a CRISPR/Cas12a-driven small molecule-induced dual-cycle strategy was developed based on the immune competition method. The key to signal amplification is the mutual activation and acceleration between Cycle 1 triggered by the small molecule and Cycle 2 driven by CRISPR/Cas12a. Impressively, small molecules have been successfully incorporated into the dual-cycle strategy, which achieves a low detection limit (3.1 pg/mL) and a wide linear range (from 10 pg/mL to 50 μg/mL). Moreover, the designed biosensor was successfully employed to evaluate the PQ residual level in real samples and showed effective implementation for the bioanalysis of small molecule targets and pesticide residue-related food safety.

E-commerce Terintegrasi WebGIS untuk IKM & UMKM di Provinsi Kepulauan Bangka Belitung dengan Agile Development

The rapid growth of Small and Medium Industries (IKM) as well as Micro, Small and Medium Enterprises (UMKM) in the Bangka Belitung Islands Province do not coincide with the dissemination of the information about their whereabouts to the public and the supervision by the Department of Labor, Industry and Trade (Disperindag). Moreover, it’s marketing, promotion, and administrative processing are still caried out in a traditional way causing ineffectiveness in obtaining profits and managing the business. Therefore, new innovations are needed i.e. an E-commerce that is equipped with a WebGIS map and is monitored and managed by the Disperindag. The development of the said E-commerce are using Agile Development with Scrum method which means it’s development are divided into some small cycle called Sprint, where each Sprint activity consists of Sprint Planning, Daily Scrum, Sprint Review, and Sprint Retrospective. Then, the test was carried out with the Technology Acceptance Model (TAM) using a 5-point Likert measurement scale to determine the acceptance of the system by the users and User Acceptance Testing (UAT) with Blackbox Testing. Last but not least, the obtained results stated that the system meets the user’s request and was accepted with a 91,47% of Perceived Usefulness, 89,24% of Perceived Ease of Use, and 90,84% of Behavioral Intention.

The Effects of Government Expenditure on the Output: A Real Business Cycle Analysis for the Romanian Economy

Abstract One of the most researched topics in macroeconomics is the development and implementation of Real Business Cycle models. This article presents a small Real Business Cycle model, which is built for the Romanian economy, with data from the 2nd quarter of 1995 through the 3rd quarter of 2022. The main aim of this analysis is to assess the historical influence of exogenous and government spending shocks on economic growth. In order to obtain accurate results, we implemented a Bayesian estimation technique for calculating the parameters of the model. The main findings indicate the significant exogenous shocks effect on the Romanian economy, and the way in which government spending had a positive effect on increasing economic growth for the period between the 1st quarter 2000 and the 3rd quarter of 2022.

Cycle Slip Detection By Combining TECR And Reconstructed Doppler Integral Method

Poor observation environment and other factors lead to the whole cycle slips of carrier phase observation value, which affects the positioning accuracy. There are detection loopholes in the traditional cycle slips detection methods, especially the small value cycle slips, equivalent cycle slips and special value cycle slips are difficult to detect. A method combining Total Electron Contents Rate (TECR) and Doppler Value Reconstruction is proposed to solve the deficiency of cycle slip detection. Based on Doppler observations and Doppler detection method, the Doppler observations are reconstructed. This method improves the accuracy of Doppler observations. The proposed method has been verified that the reconstructed Doppler observations can improve the detection accuracy of small cycle slips, and can accurately detect any large value, small value of 1 cycle, Both frequency equivalent cycle slips and special value cycle slips can be accurately detected.

Singular perturbations of generalized Holling type III predator-prey models with two canard points

We study the coexistence of limit cycles in a predator-prey model of Leslie type with generalized Holling type III functional response. When the prey reproduces much faster than the predator, we prove for this model that: (i) the existence of the configuration of one large stable limit cycle enclosing two small unstable limit cycles, (ii) the cyclicity of singular double-head canard cycles is three and reached, and (iii) the coexistence of two stable limit cycles surrounding three equilibria. The last result gives a positive answer to Coleman's problem on the coexistence of two ecologically stable limit cycles in predator-prey models.

A Cycle Slip Detection and Repair Method Based on Inertial Aiding for BDS Triple-Frequency Signals

Cycle slip detection and repair is a prerequisite to obtain high-precision positioning based on a carrier phase. Traditional triple-frequency pseudorange and phase combination algorithm are highly sensitive to the pseudorange observation accuracy. To solve the problem, a cycle slip detection and repair algorithm based on inertial aiding for a BeiDou navigation satellite system (BDS) triple-frequency signal is proposed. To enhance the robustness, the INS-aided cycle slip detection model with double-differenced observations is derived. Then, the geometry-free phase combination is united to detect the insensitive cycle slip, and the optimal coefficient combination is selected. Furthermore, the L2-norm minimum principle is used to search and confirm the cycle slip repair value. To correct the INS error accumulated over time, the extended Kalman filter based on the BDS/INS tightly coupled system is established. The vehicular experiment is conducted to evaluate the performance of the proposed algorithm from a few aspects. The results indicate that the proposed algorithm can reliably detect and repair all cycle slips that occur in one cycle, including the small and insensitive cycle slips as well as the intensive and continuous cycle slips. Additionally, in signal-challenged environments, the cycle slips occurring 14 s after a satellite signal outage can be correctly detected and repaired.

The short-range and remote analysis of virtual water trade in China

The pattern of virtual water trade within a region or region has a certain complexity. This paper uses multi-regional input-output models, local and tele-coupling theory, and geographical detectors to analyze the short-range and remote spatial pattern, change trends, and influencing factors of China's virtual water trade, which has essential research significance for the sustainable development and utilization of water resources. The results are as follows: (1) The water footprint and virtual water trade of each province in China are more likely to occur between the provinces close to each other, the local distance average distance is below 500 km, and the remote average distance is between 1100 km and 2000 km; (2) China's short-range inflow and outflow water footprint has always been the main dependent part of China's consumption and production end water resources, especially the local water footprint. The contribution of the remote water footprint has gradually been "replaced" by the short-range water footprint, and water resources only form a "small cycle" between the local and surrounding areas, becoming the main pattern of sustainable utilization of water resources in China; (3) The flow pattern of water resources in China still has a spatial imbalance and agglomeration effects. Regions with abundant water resources are net inflow and net import regions in both short-range and remote, and the net inflow and net outflow values in remote are higher than those in short-range; (4) The virtual water trade in all provinces of China tends to be close to each other. The "flow" in the trade network is mainly concentrated in the link path below 800 km. The interaction of various "flows" in short-range and remote virtual water trade results in fewer "flows" on one side and more on the other side in the industrial link path. Local virtual water trade has become an important guarantee and foundation for the utilization of water resources in all provinces and an important auxiliary to the total import virtual water trade; (5) The correlation of socio-economic factors to China's short-range and remote virtual water trade is higher than that of natural factors and scientific and technological factors. The interaction of factors contribution of a single factor more thoroughly and even far exceeds the sum of the contribution of two single factors, which can better explain the formation and change of near and long-distance virtual water trade patterns and flow on the link path.

Synchronization of Coupled Phase Oscillators with Stochastic Disturbances and the Cycle Space of the Graph

The synchronization stability of a complex network system of coupled phase oscillators is discussed. In case the network is affected by disturbances, a stochastic linearized system of the coupled phase oscillators may be used to determine the fluctuations of phase differences in the lines between the nodes and to identify the vulnerable lines that may lead to desynchronization. The main result is the derivation of the asymptotic variance matrices of the phase differences which characterizes the severity of the fluctuations. It is found that the cycle space of the graph of the system plays a role in this characterization. With theory of the cycle space, the effect of forming small cycles on the fluctuations is evaluated. It is proven that adding a new line or increasing the coupling strength of a line affects the fluctuations in the lines in any cycle including this line, while it does not affect the fluctuations in the other lines. In particular, if the phase differences at the synchronous state are not changed by these actions, then the affected fluctuations reduce.

Momentum spirals in multiphoton pair production revisited

Spirals in multiphoton pair production are revisited by two counter-rotating fields with time delay for different cycles in pulse. Novel findings include that for subcycle fields, the remarkable spiral structure in the momentum spectrum can be still caused by a large time delay compared to the previous study for supercycle case where it is easier to be generated by a small time delay. And also there exist a range of critical polarization values for the spirals appearance corresponding to the different cycle number. The relative phase difference between two fields causes not only severe symmetry breaking of the momentum spectra pattern and spiral, but also a significant change for the shape and the number of spiral arm. Upon the number density, it is found a more sensitive to the cycle number, in particularly, it is enhanced by more than one order of magnitude for small cycle pulse, while it is increased about few times when the time delay is small. These results provide an abundant theoretical testbed for the possible experimental observation on the multiphoton pair production in future. Meanwhile, it is applicable to regard the particles momentum signatures as a new probing to the laser field information with it from the vacuum.

Bifurcation of Limit Cycles and Center in 3D Cubic Systems with Z3-Equivariant Symmetry

This paper focuses on investigating the bifurcation of limit cycles and centers within a specific class of three-dimensional cubic systems possessing Z3-equivariant symmetry. By calculating the singular point values of the systems, we obtain a necessary condition for a singular point to be a center. Subsequently, the Darboux integral method is employed to demonstrate that this condition is also sufficient. Additionally, we demonstrate that the system can bifurcate 15 small amplitude limit cycles with a distribution pattern of 5−5−5 originating from the singular points after proper perturbation. This finding represents a novel contribution to the understanding of the number of limit cycles present in three-dimensional cubic systems with Z3-equivariant symmetry.