Start-up Technique Research Articles

Preliminary compact torus injection experiments on the Keda Torus eXperiment reversed field pinch

A new compact torus injector (KTX-CTI) has been built for injection experiments on the Keda Torus eXperiment (KTX) reversed field pinch (RFP). The aim is to study the fundamental physics governing the compact torus (CT) central fueling processes. In experiments conducted under the sole influence of a 0.1 T toroidal magnetic field, the injected CT successfully penetrated the entire toroidal magnetic field, reaching the inner wall of the KTX vacuum vessel. Upon reaching the inner wall, the CT diffused both radially outward and toroidally within the vessel at a discernible diffusion speed. Moreover, the inherent helicity within the CT induced a modest KTX plasma current of 200 A, consistent with predictions based on helicity conservation. CT injection demonstrated the capability to initiate KTX discharges at low loop voltages, suggesting its potential as a pre-ionization and current startup technique. During RFP discharges featuring CT injection, the central plasma density was found to exceed the Greenwald density limit, with more peaked density profiles, indicating the predominant confinement of CT plasma within the core region of the KTX bulk plasma.

Industries, frameworks, and key drivers of lean startup: a systematic literature review

Industries, frameworks, and key drivers of lean startup: a systematic literature review

Recent Start-Up Techniques Intended for TEG Energy Harvesting: A Review

Recent Start-Up Techniques Intended for TEG Energy Harvesting: A Review

A Constant-Energy-Packet-Extraction-Based MPPT Technique With 98% Average Extraction Efficiency for Wide Range Generic Ambient Energy Scavenging Supporting 1000 × Source Resistance Range

An energy harvesting system, featuring a novel generic maximum power point (MPP) tracking technique, compatible with a wide range of transducers is presented in this work. In conventional harvesting systems, the MPP tracking requires frequent open circuiting or prior knowledge about the transducer parameters. The proposed constant-energy-packet-extraction (CEPE) technique uses the technique of increasing the rate of energy extraction by frequency modulation to reach MPP and hence eliminates the need to open circuit, as well as the need for prior knowledge about the transducer parameters. The prototype system achieves an average extraction efficiency of 98% for a wide input voltage range from 50 to 500 mV and transducers with internal impedance ranging from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3~\Omega $ </tex-math></inline-formula> to 3.5 k <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> . The converter has a peak end-to-end efficiency of 81.8%. A shared inductor-based startup technique is also integrated with the system, which can start operation from a minimum input voltage of 150 mV with minimal external components. It reuses the boost converter inductor, and hence, the system requires only one inductor and three capacitors as external components. The prototype chip is fabricated in 180-nm CMOS technology and occupies an on-chip area of 1.65 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , including startup.

Incentivizing Start-Ups and Start-Up Ecosystems in European Project Funds – the Case of Grant “Performance and Excellence in the Field of Environment and Renewable Energy through Modern Cluster Entities”

Capital providers, such as shareholders on capital markets or European funding providers, are interested in the net present value of discounted cash flow and the risks or opportunities that may contribute to financial planning in a negative or positive way. In an uncertain environment however, the lean start-up movement means venture capital is used to finance business models. The lean start-up complements the business plan via discovery driven planning. These are holistic approaches to uncertainty management in all business aspects, with a designated methodology. This methodology will be the scholarly literature review in this article, whose goal is to elaborate the reference lean start-up methodologies and their relevance in empirical data analysis, European project funding calls. European projects demand uncertainty management. The article purposes to make European funds easy to understand as their requirements are explained and the most suitable scientific solution is sought. The methodology is a descriptive case study, with instrumental value. Findings are that funding authorities, be they capital markets or public funds, benefit highly in their decisions by lean start-up techniques. The research concerns the suitability of start-up ecosystems with European funds, and the conclusion is a high interest from the latter to the former.

A Fast Startup Crystal Oscillator Using Impedance Guided Chirp Injection in 22 nm FinFET CMOS

An Impedance Guided Chirp Injection (IGCI) oscillator-based fast startup technique is proposed in this work demonstrating startup time between 5 and 100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> across a wide range of oscillator frequencies. The IGCI technique can efficiently detect the resonance frequency of the crystal and provide energy injection for fast crystal startup. The simplicity of the implementation of the IGCI circuitry enables easy porting across technology nodes and interfacing with different oscillator topologies. Compared to previous negative resistance boosting or open-loop injection techniques, the proposed IGCI achieves both faster startup and lower injection power which reduces the overall startup energy. A test chip is fabricated in Intel 22FFL technology and the measurements are performed using 38.4 MHz crystal achieving ~2.6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> faster startup than normal startup (with same biasing, load cap) without any injection. Extensive measurements are performed across different temperatures and multiple startup occurrences.

Initial characterization of electron temperature and density profiles in PEGASUS spherical tokamak discharges driven solely by local helicity injection

Local helicity injection (LHI) is a non-solenoidal startup technique that utilizes electron current injectors at the plasma edge to initiate tokamak discharges. Viable non-solenoidal startup techniques require high central Te to combat resistive losses and enhance coupling to auxiliary methods of current drive/heating. Thomson scattering measurements of LHI discharges in Pegasus showed peaked Te profiles at Ip∼0.15 MA and Bt∼0.15 T with Te,0∼100– 150 eV. These results are similar to Te profiles observed with Ohmic induction. At lower levels of Bt, LHI Te profiles were hollow with Te,0∼40 eV and Te,max≤120 eV depending upon the helicity input. Regardless of the Bt level and helicity input, the electron pressure profiles were flat/peaked with hollow JR profiles. Equilibrium reconstructions and measurements of core absolute extreme ultraviolet radiation suggest the hollow Te profiles are a result of very low resistive heating power in the core due to the edge-localized nature of LHI and low-Z line radiation losses. Estimates of Zeff from the plasma conductivity indicate averaged values of ∼1 or ∼3 assuming neoclassical or Spitzer conductivity, respectively. When auxiliary heating power from magnetic reconnection is considered, this observed LHI performance is comparable to expectations from a linear Ohmic confinement scaling estimate and a collisional stochastic confinement scaling estimate of the core plasma region.

Non‐isolated bidirectional DC–DC converters with multi‐converter functionality employing novel start‐up and mode transition techniques

This work targets reducing the mode transition time drastically, for two of the bidirectional DC–DC converters (BDCs) employed in energy storage systems, simultaneously proposing a smooth start-up process. Two different mode transition techniques are introduced for topology A (proposed) and topology B, respectively, whose transition times are much smaller than the existing transition techniques. Topologies A and B are capable of performing all basic converter operations, i.e. buck, boost, inverting buck–boost and non-inverting buck–boost in bidirectional mode, which allows the operating voltage ranges of both V 1 and V 2 to be increased perceivably. Both topologies are compared based on mode transition methodology, stress on the converter switches, inductor size and rating. A start-up technique is also advocated for both topologies so that the start-up response could be smooth. Two 400 W BDCs are designed with voltage levels of 60 and 120 V and experimentally verified for efficient start-up, mode transition and steady-state operations. Both mode-transition techniques proposed here, take 2 μs for the current reversal on the battery side from +5 to −5 A.

Is Experimentation a Substitute for Experience? The Effect of Experimentation on a Funding Platform

As entrepreneurs start new ventures, they rely on resources they do not own or fully control. In communicating with resource providers, entrepreneurs make specific choices about what they disclose, and this can have a large impact on their likelihood of obtaining the resources they need. We study the description of experimentation- and planning-related activities – prominent aspects of the process of new venture creation – to show that they help elicit support from resource providers. By analyzing 54,337 project descriptions from Kickstarter, we find that describing experimentation- and planning-related activities result in an increase in the likelihood of obtaining funding. These results are replicated through online experiments to address causality concerns. With the growing emphasis among entrepreneurs on experimentation and lean start-up techniques, this research clarifies if sharing these activities helps nascent entrepreneurs gain access to resources.

10 MHz boost converter with subthreshold voltage startup and predictive dead‐time techniques for energy‐harvesting systems

A 10 MHz synchronous boost converter with the subthreshold startup scheme and predictive dead-time control for energy-harvesting systems is presented in this study. The input feed-forward technique is adopted to achieve a fast line response, and a three-stage startup technique is proposed to realise subthreshold voltage startup without using any extra startup circuits or special devices. Moreover, the efficiency of the high-frequency converter can be improved by the proposed predictive dead-time control with a high resolution of ∼300 ps. The proposed converter is implemented in a standard 0.18 μm complimentary metal oxide semiconductor process and occupies a die area of 1.4 × 1.5 mm 2 . Experimental results show that the input voltage ranges from 0.3 to 1.5 V at 1.8 V output, and the minimum startup voltage is 0.3 V. Under V IN = 1.5 V, V OUT = 1.8 V and 150 mA load, the power efficiency can be improved by 2.6% because of the proposed predictive dead-time control. The peak efficiency can reach 90.7% under V IN = 1.5 V. The line transient response can be improved with small overshoot voltage at the output.

An Improved Mode Transition Technique for a Non-Isolated Bidirectional DC-DC Converter

This brief presents the design and analysis of improved mode transition and startup techniques for a DC-DC bidirectional converter (BDC) for battery charging/discharging applications. The BDC inductor current is controlled in such a way that the current reaches its steady state value naturally without any control effort during the transient operation of the converter. The improved mode transition method ensures suppression of large transient currents in either direction by adopting simple control methodology simultaneously reducing the time of mode transition significantly, to the order of time constant of the inductor employed in the converter. This technique is implemented by sensing the direction of inductor current and generating appropriate PWM switching to the bidirectional switches. The startup technique is essential to suppress the current transient during initial response of the BDC for either modes of operation. The start-up and mode transition logic are very effective and easy to implement. A 400 W BDC is designed, analyzed, simulated and experimentally verified for improved mode transition and smooth startup techniques.

Novel Soft-Start Technique for Grid Integration of LCL-filtered Inverters

Start-up inrush current is the major threat on the reliability of the power electronic converters which may occur due to even a micro-level mismatch in the grid synchronization of inverters. This paper presents a novel technique to limit the inrush current while simultaneously reducing the synchronizing time. A feedforward voltage loop is introduced along with a current control loop with varying weightage (gain factors). In addition, the current control loop gain is adjusted at the start-up so that it catches up faster to further reduce the inrush current. A detailed investigation of the causes of the inrush current and the effect of the control loop dynamics is carried out. The effectiveness of the proposed technique is compared with various other start-up techniques in the literature. The results are validated through simulation and experimentation.

A Low-Power Fast Start-Up Crystal Oscillator With an Autonomous Dynamically Adjusted Load

An energy-efficient fast start-up method for crystal oscillators is presented, which enables aggressive duty-cycled operation of IoT radios to minimize overall power consumption. A digitally controlled crystal oscillator using the proposed start-up technique in 90-nm CMOS is presented. Thanks to the dynamically adjusted load, the negative resistance is boosted, achieving a $13\times $ start-up time reduction and an overall power of $95\mu \text{W}$ for a 24-MHz crystal oscillator at 1 V. A fully autonomous feedback loop detects the oscillators envelop and adjusts the load capacitance at start-up. Thanks to the low-power start-up circuits, both the start-up time and the start-up energy are reduced. In addition, the robustness and versatility of the proposed method is verified by measuring quartz crystals with different frequencies and quality factors, as well as measuring against temperature, supply voltage, and load capacitance variations.

Application of transient CHI plasma startup to future ST and AT devices

Employment of non-inductive plasma start-up techniques would considerably simplify the design of a spherical tokamak fusion reactor. Transient coaxial helicity injection (CHI) is a promising method, expected to scale favorably to next-step reactors. However, the implications of reactor-relevant parameters on the initial breakdown phase for CHI have not yet been considered. Here, we evaluate CHI breakdown in reactor-like configurations using an extension of the Townsend avalanche theory. We find that a CHI electrode concept in which the outer vessel wall is biased to achieve breakdown, while previously successful on NSTX and HIT-II, may exhibit a severe weakness when scaled up to a reactor. On the other hand, concepts which employ localized biasing electrodes such as those used in QUEST would avoid this issue. Assuming that breakdown can be successfully attained, we then apply scaling relationships to predict plasma parameters attainable in the transient CHI discharge. Assuming the use of 1 Wb of injector flux, we find that plasma currents of 1 MA should be achievable. Furthermore, these plasmas are expected to Ohmically self-heat with more than 1 MW of power as they decay, facilitating efficient hand-off to steady-state heating sources. These optimistic scalings are supported by Tokamak Simulation Code simulations.

Lean Startup and the Challenges With “Hard Tech” Startups

Having recently taken a refresher course in lean startup methodology, and after teaching the core concepts for the last 10 years to a variety of audiences, it is abundantly clear to the author that lean startup techniques become a bit strained when applied to hard tech or science based startups. It is argued that lean startup alone will not suffice to create a robust product/market fit. In the case of new hard science technologies, there are more fundamental questions to be asked and answered first that will enable lean startup to eventually succeed as a technique to help establish the product-market fit. For each of the verticals, one must ask: what are the current-day treatment options? How much is the problem worth and what is the scale of the problem? What is applicability of the technology to the vertical? What is the best vertical to first enter and at what point in the supply chain? These questions revolve around selecting your first beachhead market.

An 88% Efficiency 0.1–300-&lt;inline-formula&gt; &lt;tex-math notation="LaTeX"&gt;$\mu$ &lt;/tex-math&gt; &lt;/inline-formula&gt;W Energy Harvesting System With 3-D MPPT Using Switch Width Modulation for IoT Smart Nodes

This paper presents a novel 3-D maximum power point tracking (3-D MPPT) system for energy harvesting systems (EHS) within Internet of Things (IoT) smart nodes. The proposed 3-D MPPT utilizes a switch width modulation (SWM) technique for improving power efficiency (PE) at idle ( $\mu \text{A}$ ) and heavy (>300 $\mu \text{A}$ ) load modes. The SWM eliminates the gate driver/conduction loss tradeoff in a reconfigurable switched capacitor charge pump (SCCP). The proposed SWM technique modulates the SCCP switch resistance in proportion to the load condition, input voltage, and $V_{\mathrm {gs}}$ applied. A cold startup technique is incorporated in the proposed EHS with an energy-aware algorithm for input harvester select purpose. The fabricated test chip in 65-nm CMOS technology can harvest solar and thermal energy from 0.35 V and provides a regulated output voltage at 1 V with the peak efficiency of 88% at 200 $\mu \text{W}$ and PE >60% at 100 nW.

A Quick Startup Technique for High- $Q$ Oscillators Using Precisely Timed Energy Injection

High-quality ( $Q$ ) oscillators are notorious for being extremely slow during startup. Their long startup time increases the average power consumption in duty-cycled systems. This paper presents a novel precisely timed energy injection technique to speed up the startup behavior of high- $Q$ oscillators. The proposed solution is also insensitive to the frequency variations of the injection signal over a wide enough range that makes it possible to employ an integrated oscillator to provide the injection signal. A theoretical analysis is carried out to calculate the optimal injection duration. As a proof-of-concept, the proposed technique is incorporated in the design of crystal oscillators and is realized in a TSMC 65-nm CMOS technology. To verify the robustness of our technique across resonator parameters and frequency variations, six crystal resonators from different manufacturers with different packagings and $Q$ factors were tested. The implemented IC includes multiple crystal oscillators at 1.84, 10, and 50 MHz frequencies, with measured startup times of 58, 10, and 2 $\mu \text{s}$ , while consuming 6.7, 45.5, and 195 $\mu \text{W}$ at steady state, respectively. To the authors’ best knowledge, this is the fastest, reported startup time in the literature, with >15 $\times$ improvement over prior art, while requiring the smallest startup energy (~12 nJ).

Experimental Study on Geomechanical Dilation of Oil Sands During Cold–Water Injection

Summary Steam-assisted-gravity-drainage (SAGD) processes become effective only after thermal and hydraulic communication between an injection and production well has been established during the startup operation of the well pair. Conventional steam-circulation startup operations typically take 2 to 3 months to achieve interwell communication, but reductions in the startup time can have a favorable impact on project economics. Enhancement of interwell permeability using fluid-injection (water, or steam, or solvent) strategies to promote geomechanical dilation of the oil sands has been proposed as a startup technique. These fluid-injection processes will produce complex interactions of thermal, geomechanical, and multiple-phase flow behavior in the interwell formation region. Understanding better the role that these interactions play in establishing well-pair communication will provide opportunities to improve SAGD recovery performance. A triaxial experimental program has been designed and executed to explore whether cold-water injection would be sufficient to induce enhancements in effective permeability to water from geomechanical dilation mechanisms. Sample preparation techniques were modified to allow the preparation of reconstituted, very dense water-wet/bitumen sand specimens with different fluid saturations and almost identical porosities. Reclaimed/cleaned tailings sand from oil-sands mining operations was used to prepare artificial specimens, which are representative of McMurray Formation oil sands. A water-wet or bitumen sand core plug was then tested in an environmental chamber to simulate reservoir boundary conditions in terms of stress state, temperature, and pore pressure. A set of experiments was carried out in a triaxial cell under either initial isotropic or initial anisotropic stress state. Experimental results highlight the promising potential to dramatically enhance effective permeability to water and porosity in the dilated zone using cold-water injection at modest levels of stress anisotropy. The experimental results also provide support for the development of numerical models used in predicting SAGD startup performance and proactive utilization of the dilation as startup process for in-situ oil-sands development.

Technology Focus: EOR Operations (June 2017)

Technology Focus When I started editing this section in 2015, the year after the oil-price crash, many industry commentators were predicting a strong recovery in oil price by now; instead, the concept of “lower for longer” has become the present reality. Now, many commentators expect a shortfall in supply by the mid-2020s and the effect of shorter-cycle shale oil developments to be just two of the factors affecting price in the future. Sometimes, I hear the view that, without high oil prices, enhanced oil recovery (EOR) does not have a place in the mix of projects delivering the new production needed over the next decade. However, high oil prices are not the whole story. High oil prices may cause an over-heated market that squeezes the value from EOR. By their nature, EOR projects are often longer-term investments, so investing in new EOR projects at a time when real-term costs are at their highest (pushed by the high oil price) may not be the best strategy. Significant progress in cost reduction has been made in the industry following the price downturn, not only in the direct cost of construction and operations but also through a determined drive to simplify and streamline new projects in concepts selected for facilities and wells. Through this competitive scoping, project economics can be improved to deliver more-robust investment opportunities. The discipline of a lower-for-longer world can create the conditions in which long-term investment decisions can be made. In the mix of new projects needed to fill any production shortfall in the coming decade, brownfield improved and enhanced oil recovery can compete with the alternatives available to the industry. SPE continues to play an important role in sharing best practices to allow the industry to reap the benefit of project learnings, and I hope you find that the selected papers and recommended reading provide useful insights. Recommended additional reading at OnePetro: www.onepetro.org. SPE 180755 Enhanced SAGD Startup Techniques for Improved Thermal Efficiency and Conformance—A Field-Test-Based Investigation by J.M. Dragani, Cenovus Energy, et al. SPE 180739 Results of a Polymer-Flooding Pilot in the Tambaredjo Heavy-Oil Field, Suriname by E. Delamaide, IFP Technologies, et al. SPE 183362 Successful Flood-Front and Breakthrough Prediction of Miscible WAG in a Complex Carbonate Reservoir—A Case Study by Z.U.R. Qureshi, ADCO, et al.

Effect of inoculum source and effluent recycle on the start-up performance of a modified anaerobic inclining-baffled reactor treating recycled paper mill effluent

In this study, three start-up techniques of modified anaerobic inclining-baffled reactor (MAI-BR) were performance to understand the effect of inoculum source and effluent recycle on the treatment of recycled paper mill effluent (RPME). Flocculant anaerobic sludge from a palm oil mill pond and digested anaerobic sludge from a sewage treatment plant were inoculated in the first and second start-up/phase1, respectively. Results show that high chemical oxygen demand (COD) removals of 93 and 88% were achieved in the first and second start-up/phase1, respectively. The amount of methane produced in the second start-up/phase1 within 15 d was doubled as compared to the amount produced in the first start-up, with a higher methane content of 79% (as compared to 62% in the first start-up). This result indicated that the inoculum source has a significant effect on the reactor performance. The results in the second start-up/phase2 also showed that COD removal and methane production increased up to 94% and 0.52 L CH4/d, respectively. This finding can conclude that the use of effluent recycle has a favorable effect on the performance of MAI-BR. During the first start-up, second start-up/phase1, and second start-up/phase2, the volatile fatty acid/alkalinity compartmental ratios were varied at 0.01–0.06, 0.03–0.43, and 0.02–0.14, respectively, and the overall effluent pH levels were higher than 6.5. The findings indicate the stability of the MAI-BR system in treating RPME.