bluuebunny/crossref_metadata_2025 huggingface dataset:
Fully soft switched high step‐up/down bidirectional buck/boost converter with reduced switch voltage stress
Authors: Packnezhad Mohsen , Talebi Pouria , Farzanehfard Hosein
Published: January 2023

A fully soft switched high step‐up/down bidirectional converter is presented in this paper. The high voltage conversion ratio is achieved by a pair of coupled inductors along with a switched capacitor while all active switches operate at zero voltage switching. To provide soft switching condition for the main switches and absorb the leakage inductance energy of coupled inductors, active clamp circuits are utilized for both operating modes. Furthermore, all active switches body diodes which are utilized as converter diodes turn off at zero current switching (ZCS) and thus, the reverse recovery problem is eradicated. Additionally, the voltage stress of the main switches is reduced in comparison with the basic bidirectional buck/boost converter and thus, their drain‐source resistance is relatively lower which leads to considerably lower conduction loss. All the mentioned advantages along with relatively low number of components contribute to the converter efficiency. Theoretical analysis of the proposed converter is presented in detail for both operating modes and the experimental results from the implementation of a 300 W prototype circuit confirm the validity of the converter performance. A comprehensive comparison table between the proposed converter and the recent counterpart bidirectional converters is presented to demonstrate the converter advantages.
A zero switch and sensorless reconfiguration approach for sustainable operation of roof‐top photovoltaic system during partial shading
Authors: Aljafari Belqasem , Satpathy Priya Ranjan , Thanikanti Sudhakar Babu , Haes Alhelou Hassan
Published: January 2023

Photovoltaic (PV) roof‐top systems in real‐time environments are highly susceptible to the commonly occurring scenario of partial shading that occurs due to unavoidable conditions such as the shadow of buildings and trees. The occurrence of partial shading creates a serious mismatch among the modules of PV arrays that results in severe unexpected power losses in PV arrays. The conventional and hybrid configurations used for loss mitigation in PV arrays are sometimes unreliable and incapable of generating higher power during partial shading. Hence, this paper focuses on the development of a simple and effective technique for the reliable operation of PV arrays and loss reduction during the occurrence of partial shading. The technique is applicable to arbitrary array sizes having no dynamic parts and requires no switches and sensors for implementation to enhance the performance and operation of the system. The performance and reliability of the technique have been investigated under MATLAB simulation and real‐time scenarios by comparing it with various configurations under shading. The investigation reveals a higher power output by the proposed technique with an average conversion efficiency of higher than 90% and power enhancement of 19.07% than other configurations.
Electronic spectroscopy of heptacene ions in the search for carriers of diffuse interstellar bands
Authors: Kappe Miriam , Schiller Arne , Zappa Fabio , Krasnokutski Serge A. , Wagner Marie S. , Bettinger Holger F. , Scheier Paul
Published: January 2023

Context. The absorption bands of the interstellar medium (ISM) in the optical and near-infrared regions called the diffuse interstellar bands (DIBs) have been known for almost a century, yet their origins remain largely unknown. Knowledge of molecular carriers of DIBs would allow for a much better understanding of the chemistry and physics of the ISM. Polycyclic aromatic hydrocarbons (PAHs) and, among them, polyacenes have been suggested as promising candidates for carriers of DIBs.

Aims. In this paper, we report on the spectroscopy of heptacene (Hep), the polyacene molecule consisting of seven aromatic rings in a linear arrangement, in its cationic and anionic forms (Hep+/−). The performed spectroscopic studies made it possible to accurately determine the Hep+/− absorption band positions and to conduct a direct comparison of laboratory and observational spectra.

Methods. We utilized helium-tagging action spectroscopy to measure the spectra of Hep+/− in a wide spectral range of 3000–13 000 Å. In most cases, the spectra obtained by this method can be directly compared with the observational spectra. By analyzing the spectral shift as a function of the number of attached helium atoms, we obtained precise estimates of the gas-phase band positions. Quantum-chemical computations were used to support and interpret the findings. Matrix isolation spectroscopy provided information on the spectral properties of neutral Hep and extended the spectral range for Hep+.

Results. We found several absorption bands characterized by a rather large full width at half maximum in the spectra of Hep+/−. The two most intense bands were found at 4714 ± 5 Å and 12 250 ± 12 Å for Hep+ and at 4673 ± 14 Å and 11326 ± 4 Å for Hep−. We did not find any good match between laboratory and observational spectra. In particular, the intrinsic width of the absorption bands of Hep+/− is much higher than that of most observed DIBs.

Conclusions. The non-detection of Hep+/− in the observational spectra excludes the bottom-up formation route for polyacenes in the ISM. Larger polyacene molecules could still be considered as potential carriers of DIBs in the case of an efficient top-down formation route. All currently measured polyacene ions exhibit relatively broad absorption bands. Therefore, additional spectroscopy studies of neutral polyacenes and larger polyacene ions as well as the study of possible top-down formation routes are suggested.
The invisibility of young people in family farming: a gender perspective in the semi-arid region of Ceará, Brazil
Authors: Rabelo Laudemira Silva , Burte Julien Daniel Pierre , Boillot Élie Anatole Simon , Gasmi Hela , Romão Oliveira Wellington , Fradi Fajr , Rios Mariana Machado , Martins Eduardo S.P.R.
Published: January 2023

The evolution of family farming cannot be analyzed only from the perspective of production. Since it is also a kinship unit, the family farm reveals social tensions that contribute to the migration of young people, especially for young women. This study presents an analysis of the factors that contribute to this migratory process, considering youth and gender variables. The analysis is based on a participatory diagnosis, multisectoral interviews and surveys in thirty-three communities located in the center of the Ceará State (Northeastern Brazil). The research reveals that the main factor of this migratory process is the lack of appreciation of family farming by the qualified rural youth, who participate little in decision-making. When the analysis of the migration is gender-focused, the invisibility of young women productive and reproductive work stands out as the main driver of migration to urban areas and proves to be greater than for young men. Rural youth migration will shape the rural territory and will probably change the format of family farming. Understanding its factors may help to propose public policies more adapted for family farming.
Intelligent decision support in the optimization of irrigation systems in agriculture
Authors: Kabildjanov Alexander , Okhunboboyeva Charos , Ismailov Sarvarbek
Published: January 2023

The issues of determining the optimal values of the regulatory parameters of irrigation systems engaged in the cultivation of agricultural crops are considered. Following the requirements of a market economy, the main emphasis is placed on taking into account two types of criteria: maximizing the yield of agricultural crops and minimizing monetary costs. The proposed method for solving the multi-criteria optimization problem is based on the combination of the minimax criterion and the medium-step convolution, which makes it possible to scalarize the vector optimality criterion with access to smooth optimization methods. Concerning the case of priority uncertainty according to particular optimality criteria, an intelligent algorithm is proposed based on the approximation of the preference function of the decision-maker by the fuzzy Mamdani model. The multi-criteria optimization of the irrigation system used for growing cotton results differ favorably from the average values.

The one hectare yield in the republic- increased by 2%, monetary costs - reduced by 4.5%. It could be concluded that the developed methodology makes it possible to bypass the computational difficulties that arise when solving problems of multi-criteria optimization of irrigation systems engaged in the cultivation of agricultural crops and to obtain real results in conditions of certainty and uncertainty goals.
Short-term forecasting of electricity generation by HPP's of power system of Uzbekistan
Authors: Allaev Kakhraman , Makhmudov Tokhir , Losev Denis
Published: January 2023

The article describes the possibility of using the method of least squares (LSM) to predict the production of electricity per day by hydroelectric power plants in the energy system of Uzbekistan. There are obtained predictive equations and the coefficients of the approximating functions necessary for forming these equations by using the LSM. There are presented forecasting analyses by comparing polynomial functions of the highest degree using the LSM.
Generalized models of a production system of fuzzy conclusion
Authors: Ziyadullaev Davron , Muhamediyeva Dilnoz , Abdullaev Zafar , Aynaqulov Sharofiddin , Kayumov Khasanturdi
Published: January 2023

The aim of the research is to study the models, rules, and fuzzy inference engines, which occupy the main place in the knowledgebase, and models of the logic inference engines and simulation modeling, focused on supporting the adoption of semi-structured decisions under uncertainty. This implies the relevance of the task of developing theoretical and methodological tools that provide automation of the processes of fuzzy inference systems. Research methods are the theory of fuzzy sets and fuzzy logic. New scientific results are the design and formation of a set of production rules from a given set of admissible ones, with specific values of conditions and conclusions for describing three types of fuzzy models of the processes and tasks under study. Using modules of standard algorithms and programs, algorithms and a program for solving problems of fuzzy inference systems and making semi-structured decisions based on the constructed fuzzy logic model were developed. This problem is solved by formalization methods based on the theory of algorithmization, fuzzy sets, and fuzzy inference.
Comparison of microcrack formation boundaries determined by complex of physical methods with long-term strength of expanded clay concrete under different types of stress state
Authors: Raupov Chorikul , Malikov Ganisher
Published: January 2023

This work aims to experimentally study the strength and strain of expanded clay concrete during short-term and long-term compression and tension under various loading modes.

A technique for testing expanded clay concrete under short-term and long-term compression and tension, including the boundaries of microcrack formation by a complex of physical methods (tensometric, ultrasonic pulsed, and acoustic emission), is given.

The results of tests of expanded clay concrete under short-term and long-term monotonic loading under compression and tension and low-cycle loading under compression, as well as the boundaries of microcrack formation by a complex of physical methods, are obtained. The boundaries of microcrack formation are compared with the long-term strength of expanded clay concrete under various types of stressed states. Strain diagrams of expanded clay concrete under axial compression and tension, and "ultrasound transmission speed - stress level" and "number of acoustic pulses - stress level" diagrams are also obtained.

Empirical formulas are proposed for determining the boundaries of microcracking in expanded clay concrete and the relationship between the level of long-term strength and the time of staying specimens under load in compression and tension. The results allow the formulation of several proposals and clarifications for normative documents to calculate and design lightweight concrete elements and structures.
Model for calculating the hydraulic parameters of channels with a dynamically stable section
Authors: Arifjanov Aybek , Fatxulloyev Alisher , Khujaev Ismatilla , Gafarova Aziza , Allayorov Davronjon
Published: January 2023

In today's climate change conditions, it is difficult to imagine agriculture as separate from irrigated agriculture. When taking water from the river, transferring a large number of river sediments along with water to crop fields through irrigation networks requires high carrying capacity and resistance to deformation from irrigation channels. In this process, correct assessment of the factors affecting the sedimentation of the flow and ensuring that the velocity in the channel is at the limit values determines the dynamic strength of the channels. In the paper, based on the analysis of some models representing suspended turbulent flow motion and a new generalized mathematical model based on the theory of interfering media, the equation for calculating the relative width of the channel (β) for two-phase turbulent flow containing suspended sediments and the interaction of the riverbed is taken into account. It was found that the results of this equation were very close to the results of field studies compared to existing computational methods compared with the values of field studies conducted on dynamically stable section channels and the values calculated by existing computational methods.
Establishment of possibility of transferring part of machine irrigation land to gravity irrigation
Authors: Begmatov Ilkhom , Botirov Shavkat , Mamataliev Adkham , Durdiev Oraz
Published: January 2023

The increasing shortage of energy resources and difficulties associated with repairing or replacing pumping equipment requires the search for alternative solutions to machine irrigation of land. This article substantiates the possibility of a phased transition of lands in the Bandykhan district from machine irrigation to gravity irrigation. To save money, the transition to gravity irrigation is planned to be carried out without reconstruction of the canal, obtaining the maximum benefit from water accumulation.
Control of flow in the side outflow channel
Authors: Babajanova Iroda , Bazarov Orifjan , Eshev Sobir , Babajanov Yuldash , Isakov Alisher
Published: January 2023

The article discusses the task of regulating the flow in the channel with a lateral outflow. A form of retraction channel is recommended to ensure a smooth flow. Solving the issues with water distribution along the channel route and determining the shape of these channels, providing non-cavitation and non-water current, comes down to the problem of the flow of the ideal incompressible liquid in the channels with a side drain.
Theoretical substantiation of the form of working separator bodies at pre-sowing stone soil treatments
Authors: Alikulov Saydilla , Sharipov Zayniddin , Igamberdiyev Asqar , Farmonov Erkin , Khakimov Bakhodir
Published: January 2023

The article discusses a method for planting seeds in stony soil and a device for its implementation. It has been established that the quality of seed placement in the soil significantly depends on the quality of formation of the earthy soil layer at a depth of seed placement.

A method is proposed for planting seeds in stony soil, which includes cutting off the upper layer of stony soil with its simultaneous separation, formation of stony and fine-grained layers from it and laying them alternately on top of each other, forming grooves, laying seeds on its bottom and falling asleep seeds with soil. In contrast, the depth of cut of the upper layer of stony soil is taken equal to the sum of the depth of seeding and the maximum size of stones. To implement the method, a proposed device includes a frame, a ploughshare mounted on it, and a separating grid made of several parallel wire elements, sowing machines, disc coulters, and fenders.

The economic efficiency of the proposed technical solution is associated with maintaining the period of the emergence of seedlings and, accordingly, increasing the yield of crops, as well as increasing the productivity of sowing machines.
Formation and prospects of employment of labor resources in agriculture
Authors: Berdimurodov Usmon , Berdimuratov Parakhat , Farmonov Erkin , Khakimov Bakhodir , Razikov Nuriddin
Published: January 2023

The article summarizes the characteristics of the use of labor resources in agriculture by the head of the farm, determining the level of use of resources, efficient use of labor resources, shortening the seasonal working period of labor resources in agriculture, creating an employment environment, prospects for the use of labor resources in agriculture, organization of small enterprises for the industrial surplus production of agricultural products, organization of storage rooms for agricultural products, indicators reflecting the general state of labor productivity are presented. , as well as conclusions on the effective use of labor productivity and comparison of the economic potential of farmers and peasants, conclusions on the main factor of the production process, reproduction of the labor force regardless of the ownership of the economy in agricultural production.
Diagnostics of pumping units of pumping station of machine water lifting
Authors: Toirov Olimjon , Khalikov Salikhdjan
Published: January 2023

The purpose of diagnostics is to determine the operability of the pumping units of the pumping station of the machine water lifting at a given time and to identify defects in their components. For this reason, the article presents diagnostic issues for pumping stations No. 1 - No. 6 of the Karshi main canal, designed and commissioned in 1965-1976, where 6 pumping units of the OPV11-260EG type with electric motors of the VDS-375/130-24 type are installed, vertical pumping units, shaft power – 8010 kW, rated power electric motor – 12500 kW, voltage – 10.0 kV, stator current – 825.0 A, maximum permissible temperature of the stator winding – 120 OC, bearing temperature – no more than 70 OC. Diagnostics of the main equipment involves the prompt detection of malfunctions as a result of processing sensor readings of the standard monitoring system, sensor readings are entered manually once a day, and data from monthly and special tests. Technological algorithms of vibration and thermal diagnostics are similar to those developed for vertical pumps installed at thermal power plants, the processes being diagnosed in which are similar to the processes occurring in pumping units of a pumping station. Taking into account the above tasks, algorithms have been developed for diagnosing the main components whose condition affects the performance of the pumping unit: the upper bearing, the upper crosspiece, the stator winding and core, the upper and lower guide bearings, and the electric motor bearing. Possible malfunctions of pumping unit components and ways to eliminate them are given.
Technologies and means of protection in process of managing pumping stations
Authors: Usmanov Aziz , Nigmatov Azizjon , Azizova Nigora
Published: January 2023

This paper aims to analyze automatic protection and control measures at pump stations in the event of constant accumulation of groundwater and water dripping from the pump, leading to flooding in the pump station engine room. To prevent this, the pumping station's machine room should monitor the level of groundwater and water leaks from the pump and, promptly, automatically remove excess water with a pump. The excess water is collected in special reservoirs. From these, the ERSU series sensor, which is based on a contact electrode controller, does not allow it to constantly monitor the level in the storage tank within the required limits; therefore, as a completely automated system, it is unstable and cannot support the regulatory requirements for preventing it from starting one of its technical operations. The article discusses the positive aspects of technical solutions and experimental work in the DRV5023 IC with MSP430G2131 controller and no more than 2.7 mA consumer, NE555 IC-based timer and pump mode, stable contactless sensor, sensor-based automatic monitoring, and pumping system. The results are given. (12-17 seconds.) Preparation to start the pumping process is also a standard 4.7 V. power supply circuit. The work is based on production experience and is innovative.
Evaluation of the technical condition of locomotives using modern methods and tools
Authors: Khamidov Otabek , Yusufov Abdulaziz , Kudratov Shohijakhon , Yusupov Alijon
Published: January 2023

Considering its real technical condition when planning the volume of repair of locomotive equipment is one of the most important bases for reducing the costs of using railways and the cost of transportation. Continuous monitoring of the technical condition of the locomotive in use is carried out using stationary and on-board technical diagnostic tools. The method of small deviations is now widely used in various fields of science. It is a method designed to determine the existence of a correlation between the changes in parameters describing a process or a physical phenomenon. The method is based on the fact that some of the parameters of the process, in their not so large deviations from their initial values, the relationship between these deviations can be adequately expressed using certain differential calculus ratios. The wide-band exhaust gases oxygen content sensor can continuously monitor the air excess coefficient in the locomotive diesel engine cylinders. This type of sensor is widely used in automotive diesel engine control systems. It means the indirect estimation of the engine cylinders mixture quality by the exhaust gases' oxygen content
Development of technology for manufacturing molding and core mixtures for obtaining synthetic cast iron
Authors: Turakulov Murot , Tursunov Nodirjon , Alimukhamedov Shavkat
Published: January 2023

The article presents the technology for manufacturing molding and core sands for producing synthetic cast iron and also describes the scheme of the molding-pouring line. The composition and properties of core mixtures are reflected. Shows the process of preparing the molding sand using a mixing runner.The relevance of the topic lies in the fact that the increase in cargo transportation in the world places increased demands on cast iron used to manufacture railway parts and sets new challenges in the field of metallurgy, while reliability and durability are the most important of them. The fulfillment of these requirements determines the competitiveness of products in the corresponding segment of the railway transport market.
Improvement of accident prevention measures in cases of spontaneous derailment of railway rolling stock
Authors: Yusupov Aziz , Boltaev Sunnatillo , Khudayberganov Sakijan , Toxtakxodjaeva Mafirat
Published: January 2023

There has been researched on railway station tracks to determine the method of automatically stopping motion content in cases where Motion Content has gone away on its own. Even today, there are mainly cases of spontaneous movement of the composition of the movement to the side where the slope of the Railway Station roads decreases. This leads to many casualties and accidents caused by the spontaneous movement of trains at railway stations. By applying the proposed method of automatically stopping the rolling stock without human intervention, the law of conservation of mechanics, and determining the number of brake shoes set by the system device, the losses that may occur in stopping the rolling stock are achieved. In addition, the features of equipping the places of automatic stopping of the rolling stock with devices in the case of rolling stock leaving by themselves on the existing railway station tracks were considered. Also, the algorithm of operation of the system for automatic stopping of the moving parts that have gone away on their own is given of this system safety to determine semi-Markov chain for based on the system a mathematical model of safety was created. Microprocessor to the system based on by itself gone the rest movement contents to stop intended automated from devices use there is a niche in the station ways account received devices without work to algorithms and trains movement speed mutually dependence provided without by itself moving gone movement units safety provide through accidents took is taken. This prevents potential accidents, increases the reliability of system use, and leads to cost-effectiveness in system use.
Development of vibration viscometer for industry purpose and experience of its practical
Authors: Matyakubova Parakhat , Ismatullaev Patkhulla , Shamuratov Jamshidbek
Published: January 2023

Modern viscometers are devices widely presented on the market. The main advantages of viscometers are automation, increased accuracy, and speed of measurements. That's why it is important to know about the measurement of vibrational viscosity, methods for measuring vibrational viscosity and formulas for their calculation. As well as the next views which should be considered are devices for measuring vibrational viscosity and ways to improve them. The similarities and differences between viscosity measuring instruments also help to widen the outlook on the topic. A theoretical review of methods and technical means for measuring the viscosity of liquids was carried out to achieve this goal. In conclusion, we can say that vibratory viscous measuring equipment based on a new design and measurement method is promising.
Ostracoda (Crustacea) and limnoecological characteristics of Lake Karamurat (Bolu, Turkey): Testing pseudorichness hypothesis
Authors: Külköylüoğlu Okan
Published: January 2023

To investigate the relationship between ostracod occurrence patterns, community assemblage, and abiotic factors, we sampled five sites on lake Karamurat (Bolu, Turkey) and two nearby rheocrene springs. Thirteen ostracod taxa (10 from the lake, three from the springs) were collected. Species exhibited clear habitat preferences, and lake and spring ostracods showed clear differences in their monthly and seasonal occurrences.Darwinula stevensoniandCypria ophtalmicawere the dominant species for the lake andPsychrodromuscf. fontinalisandP. olivaceuswere only reported from the springs. Ostracod Watch Model illustrated that a rare species,Notodromas monacha, was only found in May to August from the lake while two species (D. stevensoni,C. ophtalmica) were encountered from all year around. Common species also exhibited relatively high levels of ecological tolerances to multiple environmental variables. Canonical correspondence analyses explained about 91% of correlation between species and environmental variables and indicated that four variables (water temperature, dissolved oxygen, pH and electrical conductivity) most strongly influenced species occurrences. Also, binary data of sample medians showed significant (P< 0.01) differences between ostracod assemblages from 13 lakes and reservoirs compared to Lake Karamurat. A significant correlation was detected between Lake Karamurat and two other lakes (Abant and Yeniçağa) located in the same region. The Pseudorichness Ratio (noncosmopolitan/cosmopolitan species) of the lake was very low (Pr = 0.25), indicating dominancy of cosmopolitan species over noncosmopolitans. Conservation efforts should be considered to addressed increasing anthropogenic impacts to Lake Karamurat.
The effects of solar radio bursts on frequency bands utilised by the aviation industry in Sub-Saharan Africa
Authors: McKee Sarah Ruth , Cilliers Pierre Johannes , Lotz Stefan , Monstein Christian
Published: January 2023

Solar radio bursts have been associated with a number of disruptions in avionic systems. The objective of this work is to develop solar radio burst interference thresholds which account for the technical specifications of aviation-related instrumentation, instrument operating frequencies as well as industry stipulated error tolerances. Solar radio bursts are suggested to be potentially hazardous when exceeding these calculated thresholds. Particular attention is paid to the radio altimeter, an important component in aviation safety. The thresholds suggested in this work for VHF communication, GPS navigation receivers and radio altimeter frequencies are; 102, 103, and 104 sfu respectively. Solar radio burst interference (for solar radio bursts above 104 sfu) is shown to result in large errors (64–251 m) in the altitude estimates for the Frequency Modulated Continuous Waves (FMCW) radio altimeter simulated in this work.
Importance of Vitamin D Status and Nerve Conduction in Pediatric Cystic Fibrosis Patients
Authors: Polat İpek , Köse Seda Şirin , Ayanoğlu Müge , Okur Derya , Bayram Erhan , Yiş Uluç , Asilsoy Suna , Kurul Semra Hız
Published: January 2023

Cystic fibrosis is one of the most common inherited diseases. It presents with recurrent respiratory infections, pancreatic insufficiency, and growth retardation. Neurological involvement becomes more common as life expectancy increases. Chronic hypoxia, impaired glucose intolerance, autoimmune mechanisms, vasculitis changes, and micronutrient deficiencies seem to cause neuropathy in cystic fibrosis. This study was aimed to investigate peripheral neuropathy in pediatric cystic fibrosis patients. Twenty-one cystic fibrosis patients and 19 healthy control subjects between the ages of 7 and 17 years were included. Their nerve conduction study results and laboratory investigations were analyzed. Participants were classified into four groups; 1. Cystic fibrosis with vitamin D deficiency, 2. Cystic fibrosis with normal vitamin D levels, 3. Healthy subjects with vitamin D deficiency, 4. Healthy subjects with normal vitamin D levels. We found statistically significantly lower sensory median nerve sensorial nerve action potential, sensorial sural nerve conduction velocity, and motor peroneal nerve compound motor action potential in cystic fibrosis patients with vitamin D deficiency than in other cases. We also found that the main difference between cystic fibrosis and control groups was especially in patients with low vitamin D levels. Nerve damage starts at an early age, especially in cystic fibrosis patients especially those with vitamin D deficiency. Electrophysiological evaluation to assess neuropathy is important even in asymptomatic patients. Prevention of hypovitaminosis D is important to prevent neuropathy in cystic fibrosis patients.
From local modification to global innovation: How research units in emerging economies innovate for the world
Authors: Morris Shad , Oldroyd James , Allen Ryan T. , Chng Daniel Han Ming , Han Jian
Published: January 2023

More and more companies are turning to emerging markets as sources of global innovation to help transform business and society. However, building innovation capabilities in emerging markets is still elusive for most companies. To understand how some companies are successfully building these capabilities, we examined workers within R&D units in China across six foreign multinational corporations. In contrast with prior literature that emphasizes a structural view of who the workers interacted with to innovate, our inductive analysis highlights a behavioral view of how R&D unit personnel interact during the problem and solution search process. We identified two key behaviors associated with the problem and solution search: (1) observing customers in their everyday context, and (2) uncovering general knowledge principles from internal experts. Respectively, these behaviors helped R&D workers to question assumptions about existing products as they relate to customers and to apply useful principles from expert knowledge rather than copying solution templates. Our findings offer an alternative path to building global innovation capabilities in markets where structural constraints exist for the company.
The use of discourse markers in argumentative compositions by Jordanian EFL learners
Authors: Huneety Anas , Alkhawaldeh Asim , Mashaqba Bassil , Zaidan Zainab , Alshdaifat Abdallah
Published: January 2023

The aim of the present study is to investigate the use of discourse markers (DMs) in the argumentative compositions written by EFL learners at two academic stages (sophomores and seniors) majoring in English at the Hashemite University, Jordan. The significance of this study springs from its focus on the use of DMs in Jordanian EFL learners’ argumentative writings. Employing an integrated research method of qualitative and quantitative analysis, the findings revealed that both groups of participants used the same types of DMs with varying degree of frequency, namely, elaborative, contrastive, reason, inferential, conclusive, and exemplifier DMs, respectively. The sophomores were observed to employ a relatively higher number of DMs compared to the seniors, which may be ascribed to some redundant instances of DMs. The elaborative, contrastive, and reason types were the most widely used, while inferentials, conclusives and exemplifiers appeared infrequently in both groups. The analysis of individual DMs displayed that the DMs ‘and’, ‘because’, and ‘but’ were the predominant across the seniors and sophomores’ argumentative texts. This overuse of these DMs may be due to the influence of L1 of the participants and the popularity of these DMs among students and teachers of English. Additionally, the participants showed a low proficiency in using DMs since they overused largely a restricted variety of DMs at the expense of others that would be expected in the argumentative writing; some DMs were noticed either to be underused or absent. The results of Pearson’s r correlation test indicated that there was a weak positive but significant correlation between the writing quality and the use of DMs. This may be taken as a predictor of the writing quality in argumentative compositions by EFL. Pedagogically, the study emphasizes the significance of teaching DMs, where EFL learners should be taught how to use them appropriately to avoid any transference of their L1. Further research on DMs in argumentative writings in different levels of proficiency is recommended.
Career development of international medical graduates in Canada: status of the unmatched
Authors: Wang Yiming , Das Rajkumar Luke Vijendra , Lapa Tatiana , Marosan Peter , Pawliuk Rosemary , Chable Heidi D. , Lake Deidre , Lofters Aisha
Published: January 2023

With limited residency positions, the majority of international medical graduates living in Canada and other developed countries cannot work as physicians. The educational experience and career development of unmatched international medical graduates (those who are not matched to a residency position) residing in Canada have never been studied. Through an innovative collaboration of provincial international medical graduate organizations, we launched an online survey targeting the career development of unmatched international medical graduates, with 356 survey responses entering data analysis. Respondents reported that at the early career planning stage, close to a third had not had adequate knowledge of their career prospects in Canada. Although official resources are available, most respondents found that the information did not match well with reality. After arriving in Canada, educational resources for unmatched international medical graduates are scarce. The majority of them work in healthcare-related fields but reported significant difficulties finding these positions, and there were limited career training opportunities. Among respondents who were no longer pursuing residency positions and had moved on to alternate career paths, we found, unexpectedly, that 69% of them reported previous residency application experience did not contribute to their current occupation, and most were not satisfied with their current career status and continuing education opportunities. In conclusion, the unmatched international medical graduates could serve as a vital reservoir of skilled medical professionals to serve the community, especially during public health crises. Continuing education and career support of unmatched international medical graduates are crucial for their career development and should be an area of priority for policymakers. Career support, especially for alternative career paths, can be built on the current services that exist in most provinces in Canada. In addition, novel online and social media tools can be utilized to increase the outreach of these programs.
Lightwave-driven electron emission for polarity-sensitive terahertz beam profiling
Authors: Lange Simon Jappe , Hoffmann Matthias C. , Jepsen Peter Uhd
Published: January 2023

The full exploitation of advanced light sources in the terahertz (THz) frequency range requires versatile experimental tools to fully characterize the spatial, temporal, and spectral shapes of the THz electric field. Several techniques for passive THz beam profiling exist that offer information about the temporally integrated intensity. Thus, any information about the electric field itself is lost. Here, we show that a UV–visible light emission produced via a lightwave-driven field emission from single-layer metasurfaces can be used to visualize the peak electric field distribution of THz beams in real time. Our technique is scalable up to frequencies approaching the plasma frequency of the metal used for the metasurface. Uniquely, our device is sensitive to the absolute polarity of the THz lightwave. These findings demonstrate a general pathway to designing metamaterial-based field-sensitive optical detectors suitable for the entire THz and IR spectral region.
A new strategy for simultaneous photoluminescence and thermal energy storage/release: Microencapsulated phase change materials via nano-Y2O3 modified PW@CaCO3
Authors: Liu Xinyi , Guo Zhixiong , Wang Jifen , Xie Huaqing
Published: January 2023

A multifunctional microencapsulated phase change material (PW@CaCO3/Y2O3) with both photoluminescence and thermal energy storage/release properties has been prepared by in situ polymerization. The material is based on the phase change material paraffin wax (PW) as its core, and the highly thermally conductive inorganic material CaCO3 is selected as the shell material to which a nano-Y2O3 material is attached. Five samples with different amounts of nano-Y2O3 incorporated in the shell are prepared. The microscopic morphology, chemical composition, crystal structure, thermal energy storage properties, thermal conductivity, thermal stability, as well as fluorescence spectra and intensities of the samples are experimentally measured and compared. The luminescence properties of nano-Y2O3 and the light enhancement phenomenon of microencapsulated phase change materials are also analyzed. The thermal properties are investigated, and it is found that the PC-Y3 sample (i.e., the mass ratio of PW:CaCO3:nano-Y2O3 is 100:100:3.0) exhibits the best thermal performance among the five samples with a melting enthalpy of (87.5 ± 2.5)  J/g, an encapsulation efficiency of (61.9 ± 1.2)%, a thermal energy storage efficiency of (62.1 ± 1.5)%, an average specific heat capacity of (1.38 ± 0.21) kJ/(kg K) in solid phase (10–20 °C) and (1.46 ± 0.02) kJ/(kg K) in liquid phase (70–80 °C), and a thermal conductivity of (1.55 ± 0.01) W/(m K) in solid phase that is six times that of the solid PW. A study of the optical properties revealed that the microcapsules emitted blue light at an excitation wavelength of 290.0 ± 2.2 nm. The fluorescence intensity appeared to be enhanced with the addition of nano-Y2O3. This microencapsulated phase change material has potential applications in areas where synchronization of fluorescence and thermal modulation is required; for example, some specific fluorescent sensors that are very sensitive to heat should operate at a fixed low temperature.
Three-wave mixing traveling-wave parametric amplifier with periodic variation of the circuit parameters
Authors: Fadavi Roudsari Anita , Shiri Daryoush , Renberg Nilsson Hampus , Tancredi Giovanna , Osman Amr , Svensson Ida-Maria , Kudra Marina , Rommel Marcus , Bylander Jonas , Shumeiko Vitaly , Delsing Per
Published: January 2023

We report on the implementation of a near-quantum-limited, traveling-wave parametric amplifier that uses three-wave mixing (3WM). To favor amplification by 3WM, we use superconducting nonlinear asymmetric inductive element (SNAIL) loops, biased with a dc magnetic flux. In addition, we equip the device with dispersion engineering features to create a stopband at the second harmonic of the pump and suppress the propagation of the higher harmonics that otherwise degrade the amplification. With a chain of 440 SNAILs, the amplifier provides up to 20 dB gain and a 3-dB bandwidth of 1 GHz. The added noise by the amplifier is found to be less than one photon.
Grain to grain heterogeneity in PZT thin films as probed by in situ biasing XRD
Authors: Nguyen Kien , Gueye Ibrahima , Leake Steven , Le Rhun Gwenael , Gergaud Patrice , Vaxelaire Nicolas
Published: January 2023

Piezoelectric thin films are particularly difficult to model at the grain scale. Moreover, this problem is sparsely experimentally documented due to the lack of adequate methods. Here, an original methodology is proposed to study the behavior of single grains during in situ biasing. Pb(Zr,Ti)O3 films have been evaluated thanks to an in situ biasing x-ray diffraction technique performed on a synchrotron source with a sub-micronic x-ray beam. Small capacitors have been biased with DC voltage between 0 and ±20 V and at each step of bias a set of spotty Debye rings have been recorded. By selecting an appropriate region of interest, the evolution of a single grain peak has been followed. The fine analysis of these peaks allows to calculate the effective piezoelectric coefficient d33,eff, the proportion of each domain variants, the tetragonality inside each grain, as well as their evolution during the electrical biasing. A higher heterogeneity in samples with morphotropic phase boundary composition is observed. This study contributes to a better understanding of the local behaviors in piezo/ferroelectric polycrystalline films and in the improvement of their performance for different applications.
Rheology of Pseudomonas fluorescens biofilms: From experiments to predictive DPD mesoscopic modeling
Authors: Martín-Roca José , Bianco Valentino , Alarcón Francisco , Monnappa Ajay K. , Natale Paolo , Monroy Francisco , Orgaz Belen , López-Montero Ivan , Valeriani Chantal
Published: January 2023

Bacterial biofilms mechanically behave as viscoelastic media consisting of micron-sized bacteria cross-linked to a self-produced network of extracellular polymeric substances (EPSs) embedded in water. Structural principles for numerical modeling aim at describing mesoscopic viscoelasticity without losing details on the underlying interactions existing in wide regimes of deformation under hydrodynamic stress. Here, we approach the computational challenge to model bacterial biofilms for predictive mechanics in silico under variable stress conditions. Up-to-date models are not entirely satisfactory due to the plethora of parameters required to make them functioning under the effects of stress. As guided by the structural depiction gained in a previous work with Pseudomonas fluorescens [Jara et al., Front. Microbiol. 11, 588884 (2021)], we propose a mechanical modeling by means of Dissipative Particle Dynamics (DPD), which captures the essentials of topological and compositional interactions between bacterial particles and cross-linked EPS-embedding under imposed shear. The P. fluorescens biofilms have been modeled under mechanical stress mimicking shear stresses as undergone in vitro. The predictive capacity for mechanical features in DPD-simulated biofilms has been investigated by varying the externally imposed field of shear strain at variable amplitude and frequency. The parametric map of essential biofilm ingredients has been explored by making the rheological responses to emerge among conservative mesoscopic interactions and frictional dissipation in the underlying microscale. The proposed coarse grained DPD simulation qualitatively catches the rheology of the P. fluorescens biofilm over several decades of dynamic scaling.
Revisiting the electronic and optical properties of SiO2 polymorphs by hybrid functional calculations
Authors: Chen Jiaqi , Zhang Zhaofu , Guo Yuzheng , Robertson John
Published: January 2023

The structural, electronic, and optical properties of nine different polymorphs of silica are investigated with both the traditional generalized gradient approximation (GGA) scheme and the hybrid functional. These include the 4:2-coordinated systems of quartz, tridymite, cristobalite, coesite, and keatite, as well as the 6:3-coordinated stishovite. The phases with similar crystal structures tend to share analogous electronic and optical features, while these properties are different in the case of stishovite. For the 4:2-coordinated polymorphs, linear relations are firmly established between the bandgap and the static dielectric constant vs the unit cell volume, respectively. Further investigation of their refractive indices also reveals a strong linearity with the corresponding densities. Our calculation with the sX functional reproduces the experimental bandgap values well, while GGA is superior for the overall trends of their optical properties.
Resonance of “subhemispherical” water balloons: Shape analysis and frequency prediction
Authors: Chang Chun-Ti , Huang Ming-Siang
Published: January 2023

Water balloons and water drops are different objects, yet the work by Chang [“On the similarities between the resonance behaviors of water balloons and water drops,” Phys. Fluids 32, 124113 (2020)] reveals the similarities between their resonance behaviors. Chang's work focuses on the balloons with pinning angles beyond 90° (superhemispherical balloons), and the results are based on a limited number of modes. In this study, the resonance of balloons with pinning angles below 90° (subhemispherical balloons) is examined. The setup is similar to that for Chang's work, except each balloon is enlarged to possess a larger inertia, and a correlation-based method is adopted to visualize the balloon's oscillation. With these improvements, this study successfully discovers more than 37 modes, many of them have not been reported in the literature. For these modes, a catalogue is constructed to demonstrate their one-to-one correspondence to the modes of drops. Additionally, a scaling scheme is proposed to assimilate the resonance frequencies of subhemispherical balloons and drops. With these, this study provides a simple framework for predicting a subhemispherical water balloon's resonance with a theory for the resonance of sessile drops on a flat plate.
Exploring three-body fragmentation of acetylene trication
Authors: Yadav Jatin , Safvan C. P. , Bhatt Pragya , Kumari Pooja , Singh Jasmeet , Rajput Jyoti
Published: January 2023

The three-body breakup of [C2H2]3+ formed in collision with Xe9+ moving at 0.5 atomic units of velocity is studied by using recoil ion momentum spectroscopy. Three-body breakup channels leading to (H+, C+, CH+) and (H+, H+, C2+) fragments are observed in the experiment and their kinetic energy release is measured. The breakup into (H+, C+, CH+) occurs via concerted and sequential modes, whereas the breakup into (H+, H+, C2+) shows only the concerted mode. By collecting events coming exclusively from the sequential breakup leading to (H+, C+, CH+), we have determined the kinetic energy release for the unimolecular fragmentation of the molecular intermediate, [C2H]2+. By using ab initio calculations, the potential energy surface for the lowest electronic state of [C2H]2+ is generated, which shows the existence of a metastable state with two possible dissociation pathways. A discussion on the agreement between our experimental results and these ab initio calculations is presented.