Start-up Procedure Research Articles

Incentive Schemes Increase Risky Behavior in a Safety-Critical Working Task: An Experimental Comparison in a Simulated High-Reliability Organization

As financial incentive schemes have the tendency to increase risky behavior, we analyzed their effect on rule-related behavior in a safety-critical task. We compared risky behavior (in terms of the amount of rule violations) between three payment condition: continuous, up-front, and bonus pay. Fifty-nine participants were trained as production personnel to conduct a start-up procedure of a simulated wastewater treatment plant, representing a high reliability organization. During the 5-h experimental study, risky behavior could have been applied 48 times while building a simulated production year. The results show that the conditions with an incentive scheme (up-front and bonus pay) led to significantly more rule violations than the condition with continuous payment without an incentive scheme. Our study highlights the general increased risk effect of incentive schemes and provides a starting point for industries to assess their implicit and explicit incentive schemes.

Drastic Events and Gradual Change Define the Structure of an Active Copper-Zinc-Alumina Catalyst for Methanol Synthesis.

The copper‐zinc‐alumina (CZA) catalyst is one of the most important catalysts. Nevertheless, understanding of the complex CZA structure is still limited and hampers further optimization. Critical to the production of a highly active and stable catalyst are optimal start‐up procedures in hydrogen. Here, by employing operando X‐ray absorption spectroscopy and X‐ray diffraction, we follow how the industrial CZA precursor evolves into the working catalyst. Two major events in the activation drastically alter the copper‐ and zinc‐containing components in the CZA catalyst and define the final working catalyst structure: the reduction of the starting copper(II) oxide, and the ripening and re‐oxidation of zinc oxide upon the switch to catalytic conditions. These drastic events are also accompanied by other gradual, structural changes. Understanding what happens during these events is key to develop tailored start‐up protocols that are aimed at maximal longevity and activity of the catalysts.

Methane production in a UASB reactor from sugarcane vinasse: shutdown or exchanging substrate for molasses during the off-season?

Operational strategies to maintain the potential for organic matter removal and methane production were applied to a pilot scale UASB reactor fed by vinasse. The beginning of the research took place after interrupting the system feeding for 5 weeks. Three consecutive phases were carried out. In Phase I, the UASB's restart with vinasse was studied; in Phase II, sugarcane molasses was used to replace vinasse; and in Phase III, resuming the vinasse operation was evaluated. In the whole experiment, the reactor maintained values close to 80% of COD removal efficiency. Phase I presented productivity and methane yield reaching 10.24 L CH4·L−1·day−1 and 0.40 L CH4·g−1 CODr, indicating the system's recovery capacity after shutdown. Exchanging vinasse for molasses (Phase II) caused a reduction of 69.7% in methane production, which was 3.10 L CH4·L−1·day−1. After resuming vinasse feeding (Phase III), the methane production was 1.19 L CH4·L−1·day−1. The results led us to conclude that after a period of feeding interruption, the reactor start-up procedure was more adequate than the strategy of replacing vinasse with molasses to maintain methane production.

Effect of temperature history on the irradiation behavior of vanadium alloy irradiated with the MARICO-II rig in a fast reactor, JOYO

The irradiation behavior of vanadium alloys was examined to evaluate the effect of temperature history during reactor operation. Irradiation experiments were performed in a fast reactor, Joyo, with an irradiation-temperature-controlled irradiation rig, MARICO-II. In-core irradiation rigs that control the irradiation temperature and are not influenced by reactor power were used. Irradiation conditions with or without the MARICO-II rig were performed. Significant differences in irradiation hardening and swelling behavior in undersized vanadium binary alloys were visible between temperature-controlled and conventional rigs. The temperature history affects the microstructural evolution, especially the nucleation and growth of voids during startup and shutdown procedures. No difference was observed in the vanadium alloys with oversized solute atom because the vacancy migration was suppressed by tight binding between oversized solute atoms and vacancies during irradiation. V–4Cr–4Ti–(Si,Al,Y) alloys showed significant irradiation hardening at high-temperature irradiation even though the contribution of dislocation and precipitates for irradiation hardening was insufficient to satisfy the measured irradiation hardening. The significant irradiation hardening in the V–4Cr–4Ti–(Si,Al,Y) alloys may be caused by transmission-electron-microscope-invisible clusters including minor elements (Si, Al, Y) that were formed at a high temperature during irradiation.

Flow-induced pulsations in Francis turbines during startup - A consequence of an intermittent energy system

Hydraulic turbines are increasingly responsible for regulating the electric grid, due to the rapid growth of the intermittent renewable energy resources. This involves a large increase in the number of starts and stops, which cause severe flow-induced pulsations and fluctuating forces that deteriorate the machines. Better knowledge of the evolution of the flow in the machines during transients makes it possible to avoid hazardous conditions, plan maintenance intervals, and estimate the costs of this new kind of operation. The present work provides an in-depth and comprehensive numerical study on the flow-induced pulsations and evolution of the flow field in a high-head model Francis turbine during a startup sequence. The flow simulation is carried out using the OpenFOAM open-source CFD code. A thorough frequency analysis is conducted on the fluctuating part of different pressure probes and force components, utilizing Short-Time Fourier Transform (STFT) to extract the evolution of the frequency and amplitude of pulsations. Low-frequency oscillations are detected during the startup, which are induced by the complex flow structure in the draft tube. A decomposition is performed on the draft tube pressure signals, and the variations of the synchronous (plunging) and asynchronous (rotating) modes are studied. The plunging mode is stronger at minimum and deep part load conditions, whereas the rotating mode is dominant during the presence of the Rotating Vortex Rope (RVR) at part load. The velocity field in the draft tube is validated against experimental data, and the complex flow structures formed during the startup procedure are explained using the λ2 vortex identification method.

A 0.32 nW–1.07 µW All-Dynamic Versatile Resistive Sensor Interface With System-Level Ratiometric Measurement

An ultra-low power, energy efficient, and versatile resistive sensor interface for energy constrained internet-of-things applications is presented. The sensor interface includes an efficiently duty-cycled current digital-to-analog converter (I-DAC) and an asynchronous successive approximation register (SAR) analog-to-digital converter (ADC), which enables a fully-dynamic operation. A fast start-up circuit is used in the duty-cycled I-DAC to speed up the start-up procedure and to minimize the energy consumption. A system-level correlated double sampling (CDS) technique is employed to suppress ADC offset and 1/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$f$ </tex-math></inline-formula> noise. To tackle the limited robustness against supply and temperature variations observed in a previous implementation of the sensor interface, a system-level ratiometric measurement (SRM) approach is employed in an updated design, which is described here in detail. The chip is fabricated in 65nm CMOS technology. Thanks to the all-dynamic nature, measurement rates from 0.1S/s to 12.5kS/s can be supported with an inherent scaling of power over 3 orders of magnitude. A reported lowest power consumption of 0.32nW is achieved at 0.1S/s. Adaptable resolution with efficient scaling of power can also be achieved by adjusting sensor interface settings and/or using oversampling and averaging. The achieved figure-of-merit (FoM), which ranges from 98 to 552fJ/conv-step is also the lowest among prior designs. Thanks to the SRM approach, only 3.6%/V and 21ppm/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^\circ \text{C}$ </tex-math></inline-formula> supply and temperature sensitivity are obtained, respectively.

Segmentation, business environment and global informational efficiency of emerging financial markets

The study investigates global information diffusion into emerging markets (EM) security prices. It explores the role of financial market segmentation and the business environment in describing global information production by emerging markets securities. Using Kalman smoother and variance decomposition techniques, the study estimates the global informational efficiency of emerging markets securities. It finds that global informational efficiency is time varying. Similarly, increased market segmentation, strength of legal rights, and rising ADR cost minimise global information diffusion into emerging markets security prices. Additionally, improved business start-up procedures, framework for resolving insolvency and financial market depth facilitate the incorporation of global information into security prices. The evidence shows the need for emerging markets to implement policies geared towards improving the global integration of their financial markets, enhancing the business environment, and developing cost effective and adequate framework for resolving insolvency and business related disputes. This is necessary in ensuring the diffusion of global news to emerging market security prices and consequently attracts investments into emerging economies.

Tracking raw material flow through a continuous direct compression line Part I of II: Residence time distribution modeling and sensitivity analysis enabling increased process yield

Continuous manufacturing (CM) offers advantages in quality and space–time yield compared to common batch manufacturing. However, higher yield losses due to the start-up procedure make a broad application uneconomical. This work discusses the possibility of reducing yield losses by adjusting the degree of back-mixing. Back-mixing of nonconforming material from disturbances or start-up will result in the contamination of subsequent material. Therefore, higher degrees of back-mixing cause the discharge of additional material. Choosing an advantageous setting of operational parameters may be a simple way to change the degree of back-mixing. Based on direct compression, this work demonstrates the identification of promising parameters. Therefore, step-change experiments using color-marked material in the feeder, blender, and tablet press quantify the impact of three operational parameters per device. Models for the devices and the entire process result from those measurements. Subsequently, a global variance-based sensitivity analysis identifies the most influential parameters. As a result, adjusting the minimal filling level of the feeder and the rotational feed frame speed of the tablet press reduces back-mixing by more than 30 %. At high costs of the raw materials, the resulting savings can significantly improve the economic performance of CM compared to batch manufacturing.

Advanced two phase flow model for transient molten salt receiver system simulation

In order to realistically predict and optimize the actual performance of a concentrating solar power (CSP) plant sophisticated simulation models and methods are required. This paper presents a detailed dynamic simulation model for a Molten Salt Solar Tower (MST) system, which is capable of simulating transient operation including detailed startup and shutdown procedures including drainage and refill. For appropriate representation of the transient behavior of the receiver as well as replication of local bulk and surface temperatures a discretized receiver model based on a novel homogeneous two-phase (2P) flow modelling approach is implemented in Modelica Dymola®. This allows for reasonable representation of the very different hydraulic and thermal properties of molten salt versus air as well as the transition between both. This dynamic 2P receiver model is embedded in a comprehensive one-dimensional model of a commercial scale MST system and coupled with a transient receiver flux density distribution from raytracing based heliostat field simulation. This enables for detailed process prediction with reasonable computational effort, while providing data such as local salt film and wall temperatures, realistic control behavior as well as net performance of the overall system. Besides a model description, this paper presents some results of a validation as well as the simulation of a complete startup procedure. Finally, a study on numerical simulation performance and grid dependencies is presented and discussed.

Experimental validation of a dynamic modelling of a Reversible Solid Oxide Cells (rSOCs)

The integration of Hydrogen technologies in different end-uses such as transport, electric microgrids, residential and industrial applications, will increase exponentially soon. Hydrogen as energy carrier allows more favourable energy conversion than other conventional systems and is crucial in worldwide decarbonize end uses. The production of green hydrogen, using RES, is a key area for the evolution of this technology. In this context, SWITCH is a Horizon 2020 European Project that aims to design, build and test an in-situ fully integrated and continuous multisource hydrogen production system, based on solid oxide cell technology. Reversible Solid Oxide Cell (rSOCs) technologies allow to convert renewable energy as hydrogen in the power-to-gas application (P2G) and in reversible mode is able to produce electricity from hydrogen stored, power-to-power application (P2P). rSOCs are really interesting to stabilize the random nature of RES because a combined electrolysis and fuel cell system should be able to switch between the two modes as quickly as possible in order to optimize the integration and the use of RES. However, rSOCs need a complex BoP from the thermal point of view, able to guarantee high efficiency even at partial load mode as well as easy start-up and shutdown procedures. In this work, a Stack Box Module dynamic model was developed in Modelica environment as a dynamic tool for the definition and optimization of BoP requirements. Stack model was validated in SOFC (Solid Oxide Fuel Cell) and SOE (Solid Oxide Electrolyser). The results of the simulation provide verification of the technical/thermodynamic behaviour and flexibility of a stack box of 70 cells. Dynamic modelling allows to evaluate the effect of the reagent inlet temperatures on the operation and hydrogen production/consumption in terms of yield as well as the transients between the different operative modes. Model has been validated by experimental measurements performed in the laboratory. In particular, the kinetics of the reactions governing steam methane reforming (SMR) was considered from data found in the literature, while the ASR (Area Specific Resistance) value was calibrated according to experimental data. The results of the dynamic model show as model can be a useful design and optimization tool for the SOCs technology.

Multiscale modelling of the start-up process of anammox-based granular reactors.

This work proposes a mathematical model on partial nitritation/anammox (PN/A) granular bioreactors, with a particular interest in the start-up phase. The formation and growth of granular biofilms is modelled by a spherical free boundary problem with radial symmetry and vanishing initial value. Hyperbolic PDEs describe the advective transport and growth of sessile species inhabiting the granules. Parabolic PDEs describe the diffusive transport and conversion of soluble substrates, and the invasion process mediated by planktonic species. Attachment and detachment phenomena are modelled as continuous and deterministic fluxes at the biofilm-bulk liquid interface. The dynamics of planktonic species and substrates within the bulk liquid are modelled through ODEs. A simulation study is performed to describe the start-up process of PN/A granular systems and the development of anammox granules. The aim is to investigate the role that the invasion process of anaerobic ammonia-oxidizing (anammox) bacteria plays in the formation of anammox granules and explore how it affects the microbial species distribution of anaerobic ammonia-oxidizing, aerobic ammonia-oxidizing, nitrite-oxidizing and heterotrophic bacteria. Moreover, the model is used to study the role of two key parameters in the start-up process: the anammox inoculum size and the inoculum addition time. Numerical results confirm that the model can be used to simulate the start-up process of PN/A granular systems and to predict the evolution of anammox granular biofilms, including the ecology and the microbial composition. In conclusion, after being calibrated, the proposed model could provide quantitatively reliable results and support the start-up procedures of full-scale PN/A granular reactors.

Start-up, operation and thermal-hydraulic analysis of a self-propelling supercritical CO2 heat removal system coupled to a pressurized water reactor

The supercritical carbon dioxide (sCO2) heat removal system, which is based on a closed Brayton cycle with sCO2 as a working fluid, is an innovative, self-propelling and modular heat removal system for existing and future nuclear power plants. By changing the number of CO2 cycles, the heat removal capacity can be adapted. In this paper, up to four sCO2 cycles are analyzed in interaction with a pressurized water reactor, using the thermal-hydraulic system code ATHLET and considering a long-term station blackout and loss of ultimate heat sink scenario with conservatively high and low decay heat curves. The presented start-up procedure for the heat removal system might require further optimization due to the non-linear thermal gradients. Independent from the start-up, a heat removal system with three or four CO2 cycles keeps the primary loop temperatures sufficiently low. However, with only three cycles, the core is almost uncovered, and the danger of recriticality may occur due to cold leg deboration. Controlling the turbine inlet temperature via the turbomachinery speed and subsequent shutdown of single cycles successfully adapts the operation of the heat removal system to the declining decay heat. This enables reliable decay heat removal for more than 72 h.

Marketing of Start-ups and Innovations in Agricultural Entrepreneurship

Agricultural development is a determining factor in ensuring food security. The intensification and innovation of agriculture is a prerequisite for meeting the food needs of the world’s population. Any innovative activity is Entrepreneurial and is based on the search for new ideas and their assessment; finding the necessary resources; Enterprise creation and management; receiving cash income, and personal satisfaction with the achieved result. The specificity of innovation is its riskiness, so often, investors simply ignore insufficiently substantiated projects. Currently, the due diligence procedure is gaining popularity, during which an investment study is carried out to establish the risks of a proposed capital transaction and develop a competent mayor to manage them. In the article, the authors considered the features and difficulties of marketing for startups and innovations in agricultural entrepreneurship and proposed a due diligence procedure to improve it. Due diligence is actions aimed at obtaining an objective picture of the object of financing. Due diligence is necessary both before investing, merging or buying a company and before starting any kind of cooperation with startups and innovations. The authors considered introducing the due diligence procedure and alternative ways of acquiring a business, indicated and analyzed the main stages of the financial due diligence procedure, and gave an example of the report of the diligence procedure for an agricultural startup.

A Concept for Detection of Humidity-Driven Degradation of IGBT Modules

Degradation caused by humidity affects the blocking characteristic of an insulated gate bipolar transistor (IGBT) module, leading to an increased leakage current and/or a reduced voltage blocking capability. The proposed measurement system enables the in situ detection of decreased breakdown voltage and increased leakage current. Thus, it can assess the degradation level of power modules when installed in a converter. This test is intended primarily for wind power converters and can be part of the start-up procedure of the system. The working principle has been validated on predamaged power modules arranged in half-bridge configuration, using a demonstrator implementation of the proposed approach in laboratory experiments. Due to the simplicity of the circuit, this concept is easy to integrate in existing inverter systems at a comparatively low cost.

Transient behaviour and optimal start-up procedure of closed Brayton cycle with high thermal inertia

• Precise dynamic simulation of a closed Brayton cycle with high thermal inertia is achieved based on test data and optimization algorithm. • Thermal inertia of the regenerator is critical to fast and stable full-load operation. • Initial pressure ratio takes great effect on the start-up time and start-up power consumption. • The rotor speed should be accelerated when the compressor inlet pressure arrives at 60%-65% design value. The closed Brayton cycle is promising as a power generation system owing to its output flexibility and compactness. In this study, a small closed Brayton cycle device was developed and its transient characteristics were studied experimentally and numerically. The start-up procedure for a closed Brayton cycle with considerable thermal inertia and heat dissipation was investigated. First, a modelling method based on both test data and an optimisation algorithm was developed to improve the accuracy of the dynamic simulation of the closed Brayton cycle. The optimal values of model parameters describing the thermal inertia and heat dissipation of the components were obtained by matching a group of dynamic test data using a genetic algorithm. The precision of the model was validated against additional experimental data. Then, the Pareto front of the start-up procedure, which was characterised by the time parameters concerning acceleration and injection, pressure coefficient, androtor speed, was acquired using a double-objective genetic algorithm with the goal of obtaining the smallest values for the start-up time and start-up power. Further studies showed that adjusting the sequence of acceleration and injection could help overcoming the thermal inertia of the regenerator, which was critical for fast and stable full-load operation. Firstly, selecting the appropriate initial pressure coefficient, then accelerating and then injecting was a favourable start-up procedure.

A successful start-up of an anaerobic membrane bioreactor (AnMBR) coupled mainstream partial nitritation-anammox (PN/A) system: A pilot-scale study on in-situ NOB elimination, AnAOB growth kinetics, and mainstream treatment performance

In this pilot-scale study, an innovative mainstream treatment process that couples the anaerobic membrane reactor (AnMBR) with a one-stage PN/A system was proposed for advancing the concept of carbon neutrality in the municipal wastewater treatment plant. This work demonstrates the start-up procedure of a pilot-scale one-stage PN/A system for mainstream treatment. The 255-day start-up of the one-stage PN/A system involved the cultivation of ammonium-oxidizing bacteria (AOB) from the activated sludge, suppression of nitrite-oxidizing bacteria (NOB), investigation of in-situ growth kinetics of anammox bacteria (AnAOB), and the 50-day operation of the pilot-scale AnMBR-PN/A process for natural mainstream treatment. It is verified in the pilot-scale system for the first time that the in-situ free ammonia (FA) and free nitrous acid (FNA) exposure could effectively eliminate the Nitrospira (the NOB genus) while retaining the Nitosonomas (the AOB genus) community in the suspended sludge. NOB community rebounding was not detected even at the mainstream conditions with low nitrogen concentrations (Influent ammonium concentration=38±6 mg-NH4+-N/L) by intermittent aeration to control the system dissolved oxygen (DO) below 0.5 mg/L. The results of the mainstream treatment showed that the average effluent total nitrogen (TN) in the coupled process was generally lower than 10 mg-N/L, which meets the discharge limits of most prefectures in Japan. The investigated results of the in-situ anammox bacteria (AnAOB) growth kinetics suggested that the promoted start-up strategy of taking advantage of the warm months with higher mainstream temperature to achieve the rapid in-situ growth of the AnAOB is applicable in the investigated regions. From the perspective of the removal performance of the TN and organic substance, the AnMBR-PN/A process has great potential as the layouts of the carbon-neutral mainstream wastewater treatment plants.

Closed-Loop Black Start-Up of Dual-Active-Bridge Converter With Boosted Dynamics and Soft-Switching Operation

This letter proposes a closed-loop black start-up control for the dual-active-bridge (DAB) converter. With a simple combination of the extended phase-shift and triple phase-shift modulation schemes, the DAB converter can start up with the maximum allowable precharge current while realizing soft-switching operation in the trapezoidal current mode simultaneously. Compared to the conventional start-up procedure that usually requires multiple steps of operation and parameter fine-tuning, the proposed start-up method can be implemented simply into the existing closed-loop controller and can shorten the start-up transients of the DAB converter significantly. The presented methods are validated experimentally on a downscaled DAB converter prototype.

Aeronautic pilot training and augmented reality

&lt;p class="Abstract"&gt;A pre-flight checklist requires in-depth technical knowledge of the aircraft and its dashboard, avionics, instruments, functions, and cabin layout. The student in training to be a pilot or advanced pilot, to obtain an updated certification, must know very thoroughly each instrument and its position on the flight panel. Every second spent searching for the location of an instrument, switch or indicator can waste time, resulting in a poor start-up procedure and possibly a safety hazard. The objective of this research was to obtain preliminary data to determine if the use of AR as a human interface for training can help pilots improve their skills and help them learn new flight panel layouts of different aircraft. The methodology used was Human-Centered Design (HCD) which is a multidisciplinary process that involves many actors who collaborate on design skills, including people who belong to this process such as flight instructors, students, and pilots. A mobile/tablet application prototype was created with enough detail of a flight panel of a Cessna150, an aircraft used in training flights at the Santa Catarina Aeroclub. The tests were applied in Brazil and the results showed a good response and acceptance from the users.&lt;/p&gt;

Development and validation of the interactive unit start-up procedure as a software tool in the implementation of the operator information support system at the NVNPP

This article is focused on the current issue of developing an operator information support system (OISS) for the Novovoronezh NPP II project. One of the main reasons to raise this topic is the MCR operator’s overload with data due to the greatly increased information flows related to the VVER-1200 Process I&amp;amp;C compared to the serially produced VVER-1000 power units. The other important reason, in the authors’ opinion, is the increased volume of existing procedures in hard copy due to the strengthened requirements for their registration and attempts to describe all possible failures and deviations in the programs and plant evolution sheet, which complicates the work on them. In the era of ubiquitous digitalization, the paper procedures can only distract the attention of the operator, who is overloaded with information even without that. The obvious solution is to create a system providing automatic collection and analysis of information. In addition, the functionality of the operator information support system allows the use of operating experience, thus minimizing the impact of the human factor. The lack of knowledge or experience could be especially challenging with procedures being applied infrequently, for example, for starting up and shutting down the unit. The authors consider the development and functionality of interactive procedures and applicable requirements for them. Particular attention is paid to the ergonomics of the workplace and the convenience of operating personnel working with an interactive procedure. Since the transition from the paper version of the programs can cause problems with reading the procedures and, ultimately, lead to the failure of the unit start-up time, the personnel of the operating station were directly involved in the development of the interactive programs. Based on the review results, conclusions were made about the correctness of the approaches in developing the interactive procedures and validated solutions to be disseminated for all routine operations.

Experimental study on shortcut simultaneous nitrogen removal in treating domestic sewage

To treat domestic sewage with high efficacy and low cost, the technology of shortcut simultaneous nitrogen removal was used with a new biofilm reactor. The influences on nitrogen removal effect by start-up procedure, nitrogen transformation characteristics and main factors (hydraulic retention time, dissolved oxygen, carbon-nitrogen ratio) were analyzed. The results indicate that: The reactor finished start-up of shortcut simultaneous nitrogen removal in 14 days of cultivation time after the biofilm cultured in the carrier. The ammonia nitrogen removal rate, simultaneous nitrification-denitrification rate and cumulative nitrite nitrogen rate respectively reached 91.3%, 82.7% and 63.4% in the last phase of start-up procedure. To remove ammonia nitrogen with the technology of shortcut simultaneous nitrogen removal efficiently and steadily, hydraulic retention time, dissolved oxygen, carbon-nitrogen ratio should be controlled in 3.56 hours, 1.5 mg/L and 5~8.