Start-up Stage Research Articles

A helium isotope separation cryostat with an entropy filter cooled by a G-M cryocooler

To obtain ultra-high purity 4He, a helium isotope separation cryostat including an entropy filter cooled by a G-M cryocooler was constructed. This cryostat provided possibility for continuous separation of helium isotopes. The entire separation process comprised two stages determined by the state of helium flow through the entropy filter: the startup stage and the steady stage. In this paper, the separation effect under these two stages has been studied, with 3He concentration being tested by Helix SFT™ Mass Spectrometry. The concentration of 3He were 3.31×10-8,6.39×10-10 and 2.41×10-10 for the feed helium gas, the startup stage and the steady stage. The results indicated that the concentration of 3He separated in the steady stage decreases by two orders of magnitude, and the separation effect of the startup stage is inferior to that of the steady stage. Additionally, a detailed analysis of 3He diffusion and 4He superfluid flow is presented, along with potential advancements in helium isotope separation cryostat that could benefit future industrial applications.

Curvature-Compensated Bandgap Voltage Reference with Low Temperature Coefficient

Resistance errors in bandgap reference (BGR) circuits often cause deviations in design indicators, and it is true that utilizing various compensation techniques mitigates the impact of resistance errors. In this paper, an original BGR circuit with 180 nm BCD processing is presented, which uses an improved high-order compensation and curvature compensation. The proposed BGR contains four main blocks, including a start-up stage, a first-order temperature compensation stage, a high-order temperature compensation stage, and a curvature compensation stage. Meanwhile, a trimming resistor array structure is designed to revise the temperature coefficient (TC) deviation of the test output voltage from the theoretical design value. Through wafer-level laser trimming technology, the measurement results are achieved with very little difference from the theoretical design value. The proposed BGR provides a stable reference voltage at 1.25 V with a low TC and strong power supply rejection (PSR). Within temperatures ranging from −45 °C to 125 °C, the measured TC shows an optimal value at 4.2 ppm/°C and the measured PSR shows −100 dB.

A Versatile Method for Preparation of BrCOFs Aerogels and Efficient Functionalization via Suzuki-Miyaura Reaction.

Covalent organic frameworks (COFs) aerogels solve the restrictions on processability and application caused by the insolubility and non-fusibility of powders while avoiding the inaccessibility of pore structures by dense stacking. At the current start-up stage where COFs aerogels are scarce and difficult to synthesize, design of generalized synthetic methods play an indispensable role in guiding and developing COFs aerogels. Moreover, evolving the functionality of COF aerogels is equal vital, which achieves higher performance and broader practical applications. In this work, for the first time, processable BrCOFs aerogels have been synthesized without vacuum by seven kind polar solvents, which realizes general preparation of BrCOFs aerogels. It is extremely friendly to the inapplicability for some scenarios. Furthermore, by Suzuki-Miyaura cross-coupling reaction, BrCOFs aerogels are endows with cyano groups (-CN), trifluoromethyl (-CF3) and methyl sulfonyl (-SO2-CH3) efficiently. As a proof-of-concept, BrCOFs-SO2-CH3 aerogels served as a quasi-solid electrolyte for lithium-metal batteries (LMBs), which effectively enhance the performance of batteries.

Business Model Canvas Application in Start-up Stage Business Developments - Constraints and Challenges

Business Model Canvas Application in Start-up Stage Business Developments - Constraints and Challenges

Developing an assessment model for entrepreneurship ecosystems using Hierarchical Decision Model

Entrepreneurship is a crucial driver of economic growth, necessitating the development of effective entrepreneurial ecosystems. However, there are significant gaps in the literature regarding the structured assessment of these ecosystems. This study addresses three main research gaps: the lack of structured evaluation methods, the need for a comprehensive analysis of ecosystem challenges from various perspectives, and the identification of critical factors essential for ecosystem growth. To bridge these gaps, the research introduces the Hierarchical Decision Model (HDM) as a universal assessment framework that can be adapted to different cities for creating effective entrepreneurial environments. The research methodology involved formulating perspectives and criteria through literature reviews and expert interviews. These perspectives and criteria were validated by subject matter experts and quantified by other experts to assign relative weights to each. Desirability curves were developed to measure these criteria, scored by experts. The practical applicability of the HDM was demonstrated through a case study of Riyadh, showcasing the model's effectiveness in real-world scenarios. Key findings include the identification and ranking of twenty critical criteria across five main perspectives, along with the development of desirability curves for each criterion. This provides a practical, easy-to-implement evaluation tool for policymakers. The contributions of this research are multifaceted: it introduces HDM to the field of entrepreneurship ecosystem assessment, offers a practical model for ecosystem performance measurement, and presents a framework for policy improvements. Additionally, it highlights the importance of continuous model refinement and the inclusion of diverse case studies for broader validation. Future research should focus on expanding the model to include sub-models for different regions and stages of startups’ development, ensuring its ongoing relevance and applicability. The findings show the most effective factors (perspectives and criteria) in developing entrepreneurial ecosystems and provide a method to measure the level of each criterion without requiring deep knowledge of the methodology, making it easier to implement the model in any ecosystem with any experts. The research offers an explicit case study evaluation of Riyadh's entrepreneurial ecosystem and provides recommendations for improvement areas. This study contributes to the technology management body of knowledge, particularly in the context of entrepreneurship ecosystems, presenting a universal assessment model for measuring ecosystem performance in any city. It creates an evaluation and improvement framework for policymakers to develop entrepreneurial ecosystems in their cities, ensuring continuous relevance and practicality through ongoing refinement and diverse case study applications.

Study on the transient performance of textured water-lubricated bearings considering different acceleration conditions

This study analyses the transient friction dynamics behavior of water-lubricated bearings (WLBs) with a textured structure, which explains the mechanism of texture structure influencing the hydrodynamic effect of WLB in the physical aspect. A comparison of experimental and numerical data is carried out to validate the proposed mixed lubrication model with a textured structure for WLBs. The effects of texture type, texture angle, acceleration mode, and acceleration time on the nonlinear friction dynamics properties of WLBs are investigated. The result shows that various texture structures exhibit distinct pumping effects and that the optimal friction dynamics performance of WLBs can be achieved by adopting the right herringbone texture and an acceptable texture angle. It is advisable to utilize the reverse S-shaped acceleration mode, as it may efficiently mitigate hydrodynamic shock, minimize frictional contact at the initial startup stage, and control the rotor's vibration in later stages. The brief acceleration time may result in a transient shock that hampers proper lubrication, consequently affecting the stable operation of WLBs. The study's findings offer helpful suggestions for the enhanced design of WLB structures and the mitigation of wear and vibration.

디자이너 메이커 제품으로의 창업활용 방향성에 관한 연구 - 용역 디자인을 넘어서는 창의적 가치 창출 전략

This study explores the potential and strategies of the 'designer-maker' model as a new career path for product designers. In the current design industry, where the service-oriented structure shows limitations in designers' creativity and economic independence, this research proposes an alternative model in which designers lead the entire process from product planning to sales and export. The research methods utilized include literature review, analysis of successful cases (Dyson, GARIZ, Lexon), and field observations. In particular, the study focused on the early startup stages of each case to derive practical insights. The research results confirmed that the designer-maker model provides advantages such as self-realization, expanded autonomy, and increased social influence, in addition to economic benefits. For successful transition, factors such as mindset change, choosing an appropriate time for entrepreneurship, and differentiated value propositions were identified as important elements. This study is significant in that it presents a new career option for product designers and explores the possibility of a paradigm shift in the design industry.

Examining particle size growth in twin screw granulation up to steady state with acoustic emissions

The transient evolution of granules was studied to learn new details about the underlying mechanism for continuous wet granulation in a twin-screw extruder. Sieving and a new inline PAT for particle size development was used to gain these insights. The onset for steady state was established based on observing a consistent PSD, which occurred at five times the mean residence time of the process, over a range of degrees of fill (DF; 12–30 %). The early stages of startup for granulation were captured by the inline PAT, showing different stages of granule growth for particle sizes ranging from 102 to 2230 μm. The analysis found that conveying elements have a stronger influence on granule growth at a low DF whereas the kneading zone had a stronger influence on granule growth at a higher DF. This study presents new details on this black-box process while highlighting the unique value of PAT to twin-screw granulation.

Maximizing efficiency and uniformity in SAGD steam circulation through effect of heat convection

The thermal recovery is facing the challenge of improving quality and efficiency. Steam-assisted gravity drainage (SAGD) steam circulation has a profound implications for the formal production. There is a lack of research on the situation when the steam injection pressure of injection well is lower than that of production well during startup stage. In this paper, the effects of diverse injection pressure difference on SAGD steam circulation and production stage are investigated by analytical modeling and numerical simulation, especially when the steam injection pressure of producer well is larger than that of injection well, and reliable results are obtained by temperature falloff test and model comparison validation. Meanwhile, in order to minimize the factors affecting the simulation accuracy, a sensitivity analysis of the temperature prediction model for the startup stage is carried out using Monte Carlo method and the finest possible mesh is used in the numerical simulation. The results show that:①The preheating results are faster and more uniform than the conventional preheating method when steam injection pressure of producer is greater than that of injector, and the subsequent production indexes are also superior to those of the conventional preheating method. ②The injected steam temperature had the greatest effect on the prediction accuracy of the analytical model; The finer the numerical simulation grid division, the lower the midpoint temperature of the horizontal well pair; ③An optimal range of injection pressure differences that achieves the best balance between preheating efficiency and thermal recovery effectiveness is achieved with Pprod-Pinj in the range of 400–500 kPa. ④The preheating method investigated in this paper minimizes the effect by unfavorable factors such as reservoir non-homogeneity, which holds the potential for more uniform, time-saving preheating and without the addition of field equipment.

The Influence of Pre-Lift Gate Opening on the Internal and External Flow Characteristics During the Startup Process of an Axial Flow Pump

This paper focuses on a vertical axial flow pump and employs a 1D-3D coupling method to investigate the effects of different gate pre-opening angles on the internal and external flow characteristics of the axial flow pump during startup. Through comparative analysis, the following conclusions are drawn: In the study, a fully open gate is defined as 1, while a fully closed gate is defined as 0. When starting the axial flow pump with different valve pre-opening degrees, backflow occurs within the first 20 s of startup, and the backflow rate inside the pump gradually increases with the increase in the valve pre-opening degree. At a valve pre-opening degree of 0.6, the maximum backflow rate inside the pump reaches 5.89% of the rated flow rate. When starting the pump with the valve fully open, the maximum backflow rate reaches 10.98% of the rated flow rate, and the efficiency is affected by the backflow rate. The valve pre-opening degree has little impact on the axial force acting on the impeller during startup. When starting with a valve pre-opening degree of 0.6, the internal pressure difference in the pump is minimized. Within the first 20 s of startup, the internal pressure difference in the impeller is 28.96% higher and the flow velocity is 14.62% higher with valve pre-opening degrees of 0.8 and 1.0 compared to a 0.6 degree opening. During the initial stage of pump startup, with valve pre-opening degrees of 0.8 and 1.0, the pressure fluctuation amplitude inside the pump is minimal, with maximum relative amplitudes of only 0.621 and 0.525, which are 41.00% and 28.51% lower than the maximum amplitudes at 0 and 0.2 degrees, respectively. In summary, the peak pressure inside the pump is minimized when the valve pre-opening degree is around 0.8, while the pressure difference and flow velocity are relatively lower at a pre-opening degree of 0.6. It is recommended to start the pump with a valve pre-opening degree of around 0.6 to 0.8.

Prospects and challenges in establishing entrepreneurship in post COVID-19 language and culture-related tourist attractions

This study discusses prospects and challenges facing start-up entrepreneurs in language and culture-related tourist attractions in Lombok, Indonesia. Data were collected by observing the operations of tourism entrepreneurs and interviewing the owners, workers, clients, and authorities in the industry. The data were analyzed using a mixed method where tourism sales over one year of business experience were quantitatively analyzed and where prime causes leading to profits and losses were qualitatively explicated. The findings identify six prospective opportunities and five challenges in sustainably establishing language and culture-related tourist attractions as core entrepreneurial businesses. This study enriches our understanding of what micro and small entrepreneurs experience at the early stages of business start-ups and how they respond to uncertainties facing them. The study also provides readers with an understanding of the prospects and the challenges facing small tourist-related entrepreneurs in operations at early start-up stages and serves as a reminder to small businesses about the potential challenges in their business operations. The article also recommends viable management plans to refer to as contingency strategies for probable future challenges. Furthermore, this study attempts to fill a gap in the literature on start-up entrepreneurship in language and culture-related tourist attractions.

Effects of different substrate ratios on the enrichment of anammox bacteria at low substrate concentration

Anammox bacteria (AnAOB) can be easily enriched under high temperatures and high substrate concentrations, while the application of the mainstream anammox process in low substrate municipal sewage is still relatively uncommon. Therefore, this study investigated the enrichment of AnAOB under conditions of low ammonia nitrogen and nitrite concentration at 25 °C. Results showed that using inoculated aerobic sludge, four ASBRs (R1, R2, R3 and R4) were successfully initiated with different influent substrate (NO2−-N/NH4+-N) ratios of 1.2, 1.32, 1.4 and 1.5, respectively, with reactor start-up times were 162, 150, 120 and 134 days, respectively. The values of ΔNO2--N/ΔNH4+-N in reactors were stable at 1.17, 1.32, 1.43 and 1.53 respectively. The increase in influent substrate ratios resulted in improved TN removal rates and accelerated consumption of chemical oxygen demand (COD) during the initial start-up stage. The maximum TN removal rates achieved in the four reactors were 76.09%, 79.24%, 82.82% and 82.63%, respectively. The color of sludge gradually changes from yellowish-brown to reddish-brown. Furthermore, the surface of sludge exhibited a porous mineral structure, with crater-like cavities. The dominant anammox species in the system was identified as Candida Brocadia (3.04%). According to qPCR, the abundance of hzsB in the system is 1.65 × 1012 copies/g VSS, confirming the effective enrichment of AnAOB.

기업가적 지향성과 경영성과 간 관계: 기업 수명주기 단계별 차이 분석

This study empirically analyzes the impact of the managerial environment, CEO's vision and strategy, and organizational management system on entrepreneurial orientation in domestic companies, as well as the relationship between entrepreneurial orientation and business performance. Additionally, it examines how these relationships differ across various stages of the corporate life cycle. The analysis utilizes data from the 2022 Entrepreneurial Activity Survey (Company Edition) conducted by the Korea Youth Entrepreneurship Foundation, designated as official statistics by Statistics Korea, which surveyed 3,120 companies. The results of the empirical analysis are as follows First, business environment, vision and strategy are significantly positively related to entrepreneurial orientation. In terms of firm life cycle, we find that firms in the start-up phase are slightly more sensitive to the business environment, while vision and strategy are important regardless of firm life cycle. Second, the operating system of the firm does not have a statistically significant effect on entrepreneurial orientation, and the hypothesis is rejected. It seems that it is important to have an operating system in place from the start-up stage in terms of the business life cycle. Third, a significant positive relationship was found between entrepreneurial orientation and managerial performance, and entrepreneurial orientation had a positive impact on managerial performance regardless of the firm's life cycle. The results of this study expand the factors influencing entrepreneurial orientation and provide theoretical and policy insights by analyzing the corporate life cycle, which is rarely addressed in the field of entrepreneurship, by distinguishing between the startup phase and other phases.

Full-speed domain position sensorless control strategy for PMSM based on a novel phase-locked loop

This paper proposes a full-speed-domain position-sensor-less control strategy for precise control under forward and reverse rotation conditions to address the weak convex polarity of surface-mounted permanent magnet synchronous motor (SPMSM). The strategy comprises several key stages: pre-positioning of the rotor, constant current variable frequency (I/F) start-up, construct the Luenberger State Observer, and utilization of an improved phase-locked loop (PLL) for position estimation. In the pre-positioning stage, a constant amplitude current is applied to drag the rotor to a predetermined position. Subsequently, the I/F start-up stage accelerates the motor to a predetermined speed before transitioning to the Luenberger observer for closed-loop speed control, which is based on an extended back electromotive force (back-EMF) a two-phase rotating coordinate system. The improved PLL for position and speed estimation features three components: a phase discriminator (PD), a voltage-controlled oscillator (VCO), and loop filter (LF). Experimental results demonstrate the efficacy of the proposed strategy, showing quick start-up response, speed estimation error below 2 RPM, rotor position estimation error under 0.6 degrees post-loop closure, stable tracking during rapid speed changes, and consistent accuracy and stability even under reverse rotation conditions, thereby meeting the control strategy’s objectives.

Optimum texture shape under different lubrication conditions applied to the start-up phase of journal bearings

This paper presents a parameterized model to optimize the texture units using an improved particle swarm optimization. The texture units are optimized under three lubrication states: boundary lubrication, mixed lubrication, and hydrodynamic lubrication, by utilizing the Stribeck curve. The optimal texture units can be applied to journal bearings and thrust bearings in different operating conditions to achieve maximum load-carrying capacity. The paper applies the optimal textures under the three lubrication states to the start-up stage of journal bearings to examine the lubrication performance and dynamic characteristics of the textured journal bearing system. The results demonstrate that compared to the untextured journal-bearing system, the introduction of optimal textures improves the tribological performance of the journal-bearing system, and the optimal textured units under hydrodynamic lubrication have the best friction reduction effect. Furthermore, it is found that the introduction of textures has no significant effect on the dynamic characteristics of the journal bearings.

Educational heterogeneity of the founding team of innovative start-ups: confirmations and denials

This paper focuses on the value drivers of innovative start-ups (ISUs). Few companies can overcome the start-up stage; often, the early performance is insufficient, and the potential contribution of innovation to economic development is very poor. Studies based on a firm-level perspective show mixed results on the factors affecting the growth of ISUs. Most studies emphasize the role of “external” drivers of ISUs growth, while more knowledge is required of “internal” drivers. Consequently, this research focuses on the relationship between the features of the founding teams and the early performance of ISUs. Specifically, it concentrates on education heterogeneity and analyzes whether the heterogeneity of the founding team in terms of educational level (vertical heterogeneity) and field of studies (horizontal heterogeneity) affects the Italian ISUs performance. Growth regression and unconditional quantile regression models confirm the prior literature: the educational level affects the performance and the vertical heterogeneity in the composition of the founding team is relevant for ISUs performance. However, the results also suggest interesting denials: horizontal heterogeneity does not play any role, and no moderating effect of heterogeneity is shown. These findings are strongly attractive for new ventures and policymakers.

Business Model Dynamics During the Growth Stages of Technology-Based Start-Ups

Business Model Dynamics During the Growth Stages of Technology-Based Start-Ups

Numerical investigation of the transient fluid flow and heat transfer behavior in self-driven natural circulation cooling loop

An innovative open natural circulation system is proposed in this work, which utilizes the difference of the heat flux loaded on different parts of the pipe to form a self-circulation flow of working fluid. Via CFD simulation established by embedding self-programmed code into commercial software, the transient performance of a three-dimensional natural circulation loop is studied. The results indicate that: applying uniform heat flux on the wall of the loop, the fluid flow state successively experiences three stages, i.e., liquid expansion, partial circulation, and phase change, and finally a vapor plunger blocks the pipe, leading to local heat transfer deterioration and temperature increase; applying non-uniform heat flux, the fluid can be driven to form self-circulation flow, which can not only cool the structure via convection, but also prevent bubbles from accumulating, stabilizing the maximum temperature of the system around the boiling point; further for the loop with a more complex configuration, the self-circulation can be also started but with different start modes. Therefore, the new natural circulation system can achieve effective and adaptive cooling according to the external thermal environment, avoid fluctuation and vapor block phenomenon caused by violent phase change, and reduce the driving equipment and control unit. This work provides a reference for the design of the natural circulation system applied in a non-uniform heating environment. Through transient numerical simulation of the start-up stage, the fluid flow, phase change, and heat transfer characteristics in the natural circulation loop are studied, and the start mode and mechanism are analyzed.

Investor perspective on impact-driven startups – the prioritization of certainty

PurposeIn this study, the authors dive into the assessment process of startups by impact investors. In particular, the purpose of this study is to investigate the preferences impact investors place on different social and environmental criteria. The authors build on social learning theory to understand the underlying rationale of the investors.Design/methodology/approachWith this research, the authors simplify the impact category system by conducting a systematic literature review. The authors then validate these criteria with a survey of 69 impact investors in Europe.FindingsThe results highlight the prioritization of quantifying impact and a discrepancy between essential and desirable impact categories. Due to the clear and significant results changing with the target market and startup stage focus, the authors assume a tendency of homophily of impact investors.Originality/valueWith this empirical study, the authors offer strategic implications for investors and startups as the authors decrease the complexity of impact categories while validating their significance in the impact assessment process.

Variations of flow patterns and pressure pulsations in variable speed pump-turbine during start-up process

Abstract In recent years, variable speed pumped-storage (VSPS) technology has become a hotspot of research and application due to its excellent power grid regulation capabilities. Since the speed of a VSPS unit is changeable, when switching operating conditions, more stable operating trajectories can be chosen to reduce vibration and damage. The simulations of transient processes of VSPS units normally use 1D method, which cannot judge the quality of operating conditions because of no flow pattern and pressure pulsation information. Using 3D CFD simulation based on OpenFOAM, we analyse the flow patterns and pressure pulsations when a VSPS unit with a full size frequency converter (FSFC) is in the turbine start-up process. The typical operating points in the variable speed transient trajectories obtained from 1D simulation are studied. It is found that in the initial stage of start-up, high-speed circulation flow arises in the vaneless space, leading to flow separation and large pressure pulsation. The results can provide a reference for the operation of VSPS power stations, so as to avoid operating conditions with adverse flow patterns and pressure pulsations.