Single-unit System Research Articles

Reliability for single-unit systems via virtual ages under cyclic environments

Reliability for single-unit systems via virtual ages under cyclic environments

PAM-relaxed and temperature-tolerant CRISPR-Mb3Cas12a single transcript unit systems for efficient singular and multiplexed genome editing in rice, maize, and tomato.

Class 2 Type V-A CRISPR-Cas (Cas12a) nucleases are powerful genome editing tools, particularly effective in A/T-rich genomic regions, complementing the widely used CRISPR-Cas9 in plants. To enhance the utility of Cas12a, we investigate three Cas12a orthologs-Mb3Cas12a, PrCas12a, and HkCas12a-in plants. Protospacer adjacent motif (PAM) requirements, editing efficiencies, and editing profiles are compared in rice. Among these orthologs, Mb3Cas12a exhibits high editing efficiency at target sites with a simpler, relaxed TTV PAM which is less restrictive than the canonical TTTV PAM of LbCas12a and AsCas12a. To optimize Mb3Cas12a, we develop an efficient single transcription unit (STU) system by refining the linker between Mb3Cas12a and CRISPR RNA (crRNA), nuclear localization signal (NLS), and direct repeat (DR). This optimized system enables precise genome editing in rice, particularly for fine-tuning target gene expression by editing promoter regions. Further, we introduced Arginine (R) substitutions at Aspartic acid (D) 172, Asparagine (N) 573, and Lysine (K) 579 of Mb3Cas12a, creating two temperature-tolerant variants: Mb3Cas12a-R (D172R) and Mb3Cas12a-RRR (D172R/N573R/K579R). These variants demonstrate significantly improved editing efficiency at lower temperatures (22 °C and 28 °C) in rice cells, with Mb3Cas12a-RRR showing the best performance. We extend this approach by developing efficient Mb3Cas12a-RRR STU systems in maize and tomato, achieving biallelic mutants targeting single or multiple genes in T0 lines cultivated at 28 °C and 25 °C, respectively. This study significantly expands Cas12a's targeting capabilities in plant genome editing, providing valuable tools for future research and practical applications.

Enhancing accuracy and robustness in FBS decoupling through Tikhonov regularization and unit balancing

Frequency-based Substructuring (FBS) enables the prediction of transfer functions for an assembled system based on those of a single-unit system. Conversely, FBS decoupling derives the frequency response function (FRF) of a single-unit system from the assembled system. This approach is valuable when obtaining the transfer functions of a system is challenging due to boundary conditions and deformation conditions. FBS decoupling can enhance accuracy by using additional indicator sensors. However, this often results in significant noise due to the ill-posed FRF matrix inversion. In this paper, Tikhonov regularization is employed to reduce noise-induced errors. Furthermore, this paper addresses the issue of inadequate Tikhonov regularization caused by the inherent scaling differences between the rotational and translational components within the FRF matrix. To rectify this challenge, a unit balancing method is proposed to mitigate the influence of scaling differences. This method enhances the accuracy and reliability of FRF matrix inversion processes, contributing to enhanced noise reduction and robustness in practical applications.

The Reliability and Availability Analysis of a Single-Unit System under the Influence of Random Shocks and the Variation in Demand from Production with Erlang Distribution

This study evaluates the reliability measures for a system consisting of a single unit that is subject to random shocks at random times with mismatches between demand and production. The system may sometimes be subject to random shocks leading to a system failure with probability p. The system may also fail completely for various reasons other than shocks. The unit is serviced by a technician if it is affected by a shock. However, the system may fail during operation for various other reasons, such as a programming error, human error, operational continuity and stress, and weather conditions. A single technician immediately repairs or maintains the failed unit. The system is in an operational state when there is demand or in an idle state when there is no demand. The distributions of all times in this system follow a negative exponential, while the time to repair follows a two-stage Erlang distribution. The expressions for the reliability metrics are obtained as functions of time using the Laplace transform and the supplementary variables technique. Sensitivity and relative sensitivity analyses were also performed for the system parameters. Finally, the efficiency of the system is illustrated using numerical examples.

Investigation on a heat-driven thermoacoustic refrigerator with minimal complexity

Heat-driven thermoacoustic refrigerator (HDTR) emerges as a pivotal solution to global energy challenges and carbon emissions. This study introduces a simplified single-unit HDTR as a new supplement to the heat-driven thermoacoustic refrigeration process. Featuring only one simple, direct-coupled thermoacoustic energy conversion core unit, it is designed to reduce overall system complexity. Initially, the simulation model of the single-unit system is established in Sage and compared with a two-unit HDTR, indicating that reducing the number of thermoacoustic core units decreases system complexity without compromising system performance. The onset characteristics and steady-state operational characteristics of the proposed single-unit HDTR are then experimentally tested, revealing a cooling power of 895 W with a coefficient of performance (COP) of 0.43 when the ambient and cooling temperature is 25 °C and 0 °C, respectively. Notably, a minimal onset temperature difference of 61.6 °C is obtained for the single-unit HDTR. These results showcase the possible application potential for low-grade heat recovery. A comparative analysis against existing loop HDTR systems establishes its superior performance, offering a valuable reference for contemporary HDTR assessments. This study significantly advances HDTR development, emphasizing efficiency and sustainable cooling applications.

Design space identification of a coupled two-stage batch reactor system

The design space (DS) is defined as the combination of materials and process conditions that guarantees the assurance of quality. This principle ensures that as long as a process operates within DS, it consistently produces a product that meets specifications. It was originally developed for a single unit system. Many industrial processes frequently involve multiple unit operations. Assessing the interaction of Critical Process Parameters (CPPs) with Critical Quality Attributes (CQAs) across stages enables informed decision-making and the capacity to balance different requirements. Analysis and visualization of the complex, multi-dimensional DS is a challenging task. This paper presents a framework for identification such DSs, considering both joint and decoupled strategies using a detailed analysis of a two-stage batch reactor case study. We assess and discuss the practicality and relevance of these methods.

Availability Modeling of Single Unit System Subject to Degradation Post Repair After Complete Failure Using RPGT When Repair is Perfect

In this paper we intend to analysis the behavioral of a single unit system having degradation after complete failure using RPGT. In initially the given system unit is working at full capacity which may have two types of failures, one is direct and another is through partial failure. There is a single repairman who repairs the unit on each failure. Problem is formulated and solved using RPGT to determine system parameters. System behavior is discussed with the help of graphs and tables.

Simultaneous aerobic nitrogen and phosphate removal by Pseudomonas aeruginosa SNDPR-01: Comprehensive insights on metabolic potential and mechanisms

Versatile metabolic bacteria with simultaneous nitrification–denitrification and phosphate removal (SNDPR) capabilities are promising to reduce the wastewater treatment process from a multi-unit system to a single unit system. Due to the limited study, the metabolic potential and mechanisms of nitrogen (N) and phosphate (P) removal for any SNDPR bacteria remain unknown. In this study, genomic analysis revealed various genes were present in an SNDPR isolate, Pseudomonas aeruginosa SNDPR-01, establishing diverse N- and P-metabolism potential, such as aerobic and anoxic denitrification; dissimilatory nitrate reduction to ammonia; polyphosphate (polyP) metabolism; and utilization of organic P. Phylogenetic analysis predicted that key functional genes related N and P metabolism may co-evolve with chromosomal genes, except for the norB gene, which may originate from horizontal gene transfer. Transcriptomic analysis revealed a partial nitrification and denitrification pathway (NH4+ → NO2– → NO → N2O → N2) to aerobically remove N without the involvement of conventional amoA, hao and napA genes. Unknown genes were confirmed to mediate the oxidation of ammonium to nitrite. Excellent P removal ability was aided by the synthesis of adenosine triphosphate (ATP) and polyP. The formed polyP was utilized under aerobic conditions without accumulation, which is different from traditional polyP accumulation organisms in wastewater treatment plants (WWTPs). This study will deepen the roles of SNDPR bacteria in aerobic ecological niches and enhance their application in WWTPs.

Load analysis of an off-grid hybrid power system using micro-hydro and diesel power technology in the remote areas of Bangladesh

Hybrid power technology plays an important role in the field of energy systems. This technology can be used with or without a grid by merging renewable and non-renewable sources. This study analyses electricity generation through an off-grid hybrid technology, which is composed of micro-hydro power and diesel generator power in a remote area of Bangladesh. In this investigation, some of the crucial cases will be examined, which are the optimum turbine placement with the aid of fluid flow simulation using the flow parameters, electric power production in a single power unit and hybrid power system unit, and cost analysis of the hybrid power system unit in order to inspect the feasibility of the system.

Experimental investigation of effect of extent and position of bypass openings on performance of a single unit liquid desiccant based indirect evaporative cooler

In high temperature and high humidity zones, evaporative cooling is ineffective and vapour compression systems are less energy efficient. Therefore, an alternative system is highly desirable which is effective, energy efficient and enables the use of cheap and sustainable energy sources. Indirect evaporative cooling helps in retaining humidity level of air, but is less effective in attaining lower air temperatures. To mitigate this challenge, M-cycle indirect evaporative cooling system helps in achieving sub-wet bulb temperatures. In this work, performance of a novel modified indirect evaporative M-cycle cooling system assisted by 40% aqueous Li-Cl liquid desiccant is experimentally investigated against various parameters. The cooling system used in this study is a single unit system which can perform indirect evaporative cooling, liquid desiccant dehumidification and internal cooling to the liquid desiccant. With an air velocity of 1 m/s at the inlet, the introduction of openings in between inlet and exit of the cooling system has shown a maximum improvement of 19.2% in its dew point effectiveness, with unaffected dehumidification effectiveness. Furthermore, it is observed that the dew point effectiveness is decreased with the increasing distance of openings from the inlet. The investigated cooling and dehumidification system is useful as a pre-air-conditioner to conventional air-conditioning systems and also as a stand-alone air-conditioning system.

Optimal Inspection Policy for a Three-Stage System Considering the Production Wait Time

Inspection is usually carried out periodically to update a system state such that the optimal maintenance policy can be determined. In order to obtain the best inspection and maintenance policy, existing research is focused on improving the modeling accuracy of the system failure process. Little work has been devoted to making full use of the system idle time, which is known as the production wait in production systems. In this research, the failure process of a single-unit system is modeled in three stages with consideration of its production wait time. The objective of minimizing the long-run average maintenance cost per unit time is achieved by finding the optimal length of the periodic inspection interval and renewal age for this single-unit system. By comparing this model with two two-stage inspection models, the numerical study of a real steelmaking converter confirms both the accuracy and effectiveness of the proposed inspection and maintenance model. Furthermore, the sensitivity analysis of different parameters is conducted to explore the optimal choice of maintenance strategy for different cost parameters and degradation parameters. The analysis provides useful management insights for decision-makers.

Discussion on Operational Stability of Governor Turbine Hydraulic System Considering Effect of Power System

Hydropower has grown to play an important role in power systems including increasing clean and low-carbon energies, and the effect of electric loads should be basically evaluated for the reliable operation of these systems. For the hydraulic–mechanical–electrical system of the hydropower station, the state equation model for stability evaluation was derived with typical electric load models and elastic models for pipe flow, and after experimental confirmation with a built single-unit setup for a system, the effects of different electrical loads and pipe flow models on typical hydropower systems stability were investigated in detail. The results indicate that for the built single-unit system with different load characteristics, the numerical results were basically consistent with experimental research, and the unit’s regulation performance for the dynamic load was superior to that of the static load. Evident differences existed in the effects of different electric loads on the operational stability, mainly depending on the pipe length and the corresponding models, and an optimum-order elastic model of pipe flow was preferred to reveal the dynamic interactions between different systems. Furthermore, for a typical two-unit system, the potential coupling resonance hydraulic–mechanical–electrical system is pointed out with the preferred-order elastic model of pipe flow.

Optimal Inspection Policy for a Single-Unit System Considering Two Failure Modes and Production Wait Time

In many real production systems, a system may be stopped due to a lack of demand or exhaustion of raw materials. This is known as production wait and provides a good opportunity for maintenance. Meanwhile, the increased complexity of the modern machines brings new challenges for modeling and analyzing their failure behaviors. To address these real-world problems, this article considers a single-unit system that may fail due to either hard failures or soft failures. The wait time of a system is utilized to conduct inspections and maintenance. The system is replaced when a defect is found during an inspection, a failure occurred or a prespecified age threshold is reached, whichever comes first. The cost model, which is the long-run maintenance cost per unit of time, is derived. The optimal periodical inspection interval and the threshold age to minimize the long run maintenance cost per unit of time is then obtained. A case study is conducted to demonstrate the proposed maintenance model. The study shows using the proposed maintenance model can reduce the cost. Sensitivity analysis illustrates how each cost parameter affects the optimal inspection interval and the optimal age threshold.

LOAD TRANSFER FROM HOLLOWCORE SLABS TO DELTABEAM® SLIM FLOOR BEAMS IN CASE OF A FIRE

AbstractThis paper presents the background, results and conclusions of a series of fire tests with DELTABEAM® composite beams supporting prestressed hollowcore slabs (HCS) concerning the shifted direct support in fire situation. When designing a slab system consisting of DELTABEAM® and HCS in fire situation, the current European design codes and product approvals for both products do not cover the special issues “indirect / shifted direct” and “flexible” support that arise from combining beams and HCS. A test program of single HCS unit shear tests and system fire tests has been carried out to assess these issues. The presented paper will give an overview of the test program and a detailed look at the shifted direct support situation for load transfer from the slab to the beam.

Multiplex CRISPR/Cas9-mediated raffinose synthase gene editing reduces raffinose family oligosaccharides in soybean.

Soybean [Glycine max (L.) Merr.] is an important world economic crop. It is rich in oil, protein, and starch, and soluble carbohydrates in soybean seeds are also important for human and livestock consumption. The predominant soluble carbohydrate in soybean seed is composed of sucrose and raffinose family oligosaccharides (RFOs). Among these carbohydrates, only sucrose can be digested by humans and monogastric animals and is beneficial for metabolizable energy, while RFOs are anti-nutritional factors in diets, usually leading to flatulence and indigestion, ultimately reducing energy efficiency. Hence, breeding efforts to remove RFOs from soybean seeds can increase metabolizable energy and improve nutritional quality. The objective of this research is to use the multiplex Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)/Cas9-mediated gene editing system to induce the knockout of soybean raffinose synthase (RS) genes RS2 and RS3 simultaneously to reduce RFOs in mature seeds. First, we constructed five types of multiplex gene editing systems and compared their editing efficiency in soybean hairy roots. We confirmed that the two-component transcriptional unit (TCTU) and single transcriptional unit (STU) systems with transfer RNA (tRNA) as the cleavage site performed better than other systems. The average editing efficiency at the four targets with TCTU-tRNA and STU-tRNA was 50.5% and 46.7%, respectively. Then, we designed four single-guide RNA (sgRNA) targets to induce mutations at RS2 and RS3 by using the TCTU-tRNA system. After the soybean transformation, we obtained several RS2 and RS3 mutation plants, and a subset of alleles was successfully transferred to the progeny. We identified null single and double mutants at the T2 generation and analyzed the seed carbohydrate content of their progeny. The RS2 and RS3 double mutants and the RS2 single mutant exhibited dramatically reduced levels of raffinose and stachyose in mature seeds. Further analysis of the growth and development of these mutants showed that there were no penalties on these phenotypes. Our results indicate that knocking out RS genes by multiplex CRISPR/Cas9-mediated gene editing is an efficient way to reduce RFOs in soybean. This research demonstrates the potential of using elite soybean cultivars to improve the soybean meal trait by multiplex CRISPR(Clustered Regularly Interspaced Short Palindromic Repeats)/Cas9-mediated gene editing.

Joint optimization of inspection-based and age-based preventive maintenance and spare ordering policies for single-unit systems

This paper presents a joint optimization policy of preventive maintenance (PM) and spare ordering for single-unit systems, which deteriorate subject to the delay-time concept with three deterioration stages. PM activities that combine a nonperiodic inspection scheme with age-replacement are implemented. When the system is detected to be in the minor defective stage by an inspection for the first time, place an order and shorten the inspection interval. If the system has deteriorated to a severe defective stage, it is either repaired imperfectly or replaced by a new spare. However, an immediate replacement is required once the system fails, the maximal number of imperfect maintenance (IPM) is satisfied or its age reaches to a pre-specified threshold. In consideration of the spare's availability as needed, there are three types of decisions, i.e., an immediate or a delayed replacement by a regular ordered spare, an immediate replacement by an expedited ordered spare with a relative higher cost. Then, some mutually independent and exclusive renewal events at the end of a renewal cycle are discussed, and the optimization model of such a joint policy is further developed by minimizing the long-run expected cost rate to find the optimal inspection and age-replacement intervals, and the maximum number of IPM. A Monte-Carlo based integration method is also designed to solve the proposed model. Finally, a numerical example is given to illustrate the proposed joint optimization policy and the performance of the Monte-Carlo based integration method.

Investigation of fuzzy semi-Markovian model for single unit systems with partial failure and Weibull distributed random laws

Investigation of fuzzy semi-Markovian model for single unit systems with partial failure and Weibull distributed random laws

Maintenance planning estimations and policies optimization for single-unit systems using Hawkes processes

ABSTRACT Maintenance planning and optimizations are very important issues in both theory and practice. In this paper, Hawkes processes, a tool for description of self-excited failure effects, are used to model the failure processes of single-unit systems under the assumption of neglected repair times. For such degraded single-unit systems, some maintenance planning estimations such as the distribution, mean and variance of failures or repairs by time , reliability, mean cost of maintenance, mean and variance of system lifetime are presented under the maximal entropy assumption on repair effects. Meanwhile, two optimization problems are developed by considering the lifetime mean of the single-unit system and total maintenance cost as objective functions and constraints alternatively. We have proved that both optimization problems can reduce to two simplified optimal cases, respectively, and their optimal policies are increasing stepwise sequences of increasing rates of failure rates, which greatly reduce the scope of optimal solutions. The relationships between the estimations and the optimizations are discussed. Furthermore, the detailed optimal maintenance policies for a special case are given as well including an algorithm.

Reliability assessment for a k-out-of-n: F system supported by a multi-state protective device in a shock environment

Protective devices can reduce system failure risks by protecting systems from external shocks and therefore play a critical role in the stable operations of safety–critical systems. Because of the importance of protective devices in real engineering, their performances attract extensive attentions, but existing research on protective devices are quite limited. Previous studies mainly focused on evaluating the reliability of single-unit systems equipped with binary-state protective devices by considering triggering mechanisms based on system state or shock numbers. To fill the research gaps, this paper proposes a k-out-of-n: F system with a multi-state protective device subject to external shocks, where the triggering of the protective device depends on the number of failed components in the system. Furthermore, the protective capacity of the multi-state protective device becomes weaker as the device state deteriorates due to valid shocks. After suffering a certain number of valid shocks, the protective device may transit into a lower state directly, or it can resist some additional valid shocks in the current state because of its resistance against shocks. A combination of the finite Markov chain imbedding approach and phase-type distributions is employed to analyze a series of probabilistic indices both for the system and the protective device. Finally, a case study based on a multi-cylinder diesel engine supported by a cooling system is provided to demonstrate the applicability of the proposed model.

A Study of Car Wash Wastewater Treatment by Cyclo-Flow Filtration

With the increase in transportation demand and facilities in this era and the significant improvement in people’s living standards, the annual production and sales of vehicles are steadily increasing. With this, the issues of car wash wastewater treatment and water pollution are becoming more and more serious. Car wash wastewater mainly comprises fine sand, slick oil, suspended solids (SS), and surfactants, and can be quantified as chemical oxygen demand (COD) on a normative basis. This study examines the use of cyclo-flow filtration with high filtrate flux to treat car wash wastewater to solve issue of limited space in metropolitan areas and increase the willingness of the industry to invest in car wash equipment to recover water resources. The average removal rates of SS and COD are about 81% and 43%, respectively. Compared with current technology, the price of recycled water can compensate for operating costs, requiring minimal operating space owing to the single-unit cyclo-flow filtration system.