Parallel event-triggered dynamic output feedback control for nonlinear networked systems with randomly occurring multiple communication delays.

This paper investigates the issue of parallel event-triggered (PET) dynamic output feedback control for networked control systems (NCSs) built by the discrete-time T-S fuzzy model. Initially, a novel PET dynamic output feedback controller is designed. Based on saving network resources and enhancing transmission efficiency, the PET strategy makes full use of relative and absolute triggering condition information. And the dynamic output feedback control can not only address unmeasurable states but also provide a better response to the internal information of the system. The random multiple communication delays and the ℓth-order Rice fading model with different channel coefficients, meanwhile, are both applied in the system. It is closer to the actual situation. Subsequently, new sufficient conditions of membership function dependence are proposed via the staircase function approximation method combined with Lyapunov stability. It guarantees that the system is exponentially mean square stable (EMSS) with H∞ performance. Ultimately, the presented results are validated using two examples. In the future, we will explore the correlative research of T-S fuzzy Markov jump NCSs.

Metabolically engineer Clostridium saccharoperbutylacetonicum for comprehensive conversion of acid whey into valuable biofuels and biochemicals.

As a byproduct of dairy production, the disposal of acid whey poses severe environmental challenges. Herein, an innovative solution involving metabolically engineering Clostridium saccharoperbutylacetonicum to convert all carbon sources in acid whey into sustainable biofuels and biochemicals was presented. By introducing several heterologous metabolic pathways relating to metabolisms of lactose, galactose, and lactate, the ultimately optimized strain, LM-09, exhibited exceptional performance by producing 15.1 g/L butanol with a yield of 0.33 g/g and a selectivity of 89.9%. Through further overexpression of alcohol acyl transferase, 2.7 g/L butyl acetate along with 6.4 g/L butanol was generated, resulting in a combined yield of 0.37 g/g. This study achieves the highest reported butanol titer and yield using acid whey as substrate in clostridia and marks pioneering production of esters using acid whey. The findings demonstrate an innovative bioprocess that enhances renewable feedstock biotransformation, thereby promoting economic viability and environmental sustainability of biomanufacturing.

Development of an Efficient Recombinant Protein Expression System in Clostridium saccharoperbutylacetonicum Based on the Bacteriophage T7 System.

Recombinant proteins have broad applications. However, there is a lack of a recombinant protein expression system specifically for large-scale production in anaerobic hosts. Here, we developed a powerful and stringently inducible protein expression system based on the bacteriophage T7 system in the strictly anaerobic solvent-producing Clostridium saccharoperbutylacetonicum. With the integration of a codon optimized T7 RNA polymerase into the chromosome, a single plasmid carrying a T7 promoter could efficiently drive high-level expression of the target gene in an orthogonal manner, which was tightly regulated by a lactose-inducible system. Furthermore, by deleting beta-galactosidase genes involved in lactose metabolism, the transcriptional strength was further improved. In the ultimately optimized strain TM-07, the transcriptional strength of the T7 promoter showed 9.5-fold increase compared to the endogenous strong promoter Pthl. The heterologous NADP+-dependent 3-hydroxybutyryl-CoA dehydrogenase (Hbd1) from C. kluyveri was expressed in TM-07, and the yield of the recombinant protein reached 30.4-42.4% of the total cellular protein, surpassing the strong protein expression systems in other Gram-positive bacteria. The relative activity of Hbd1 in the crude enzyme was 198.0 U/mg, which was 8.3-fold higher than the natural activity in C. kluyveri. The relative activity of the purified enzyme reached 467.4 U/mg. To the best of our knowledge, this study represents the first application of the T7 expression system in Clostridium species, and this optimized expression system holds great potential for large-scale endotoxin-free recombinant protein production under strictly anaerobic conditions. This development paves the way for significant advancements in biotechnology and opens up new avenues for industrial applications.

Event-triggered dissipative double asynchronous controller for interval type-2 fuzzy semi-Markov jump systems with state quantization and actuator failure.

The issue of strictly exponential dissipation stability for the interval type-2 fuzzy semi-Markov jump systems is investigated. A quantized method is proposed to cope with uncertainties, actuator failures, time-varying delay and nonlinear disturbance of the system. To avoid the waste of network resources, the mode-dependent event-triggered mechanism with particular threshold parameters is used to screen the conveyed signal. Due to that the premise variables and the modes tend to be mismatched between the system and the controller, a novel double asynchronous controller is proposed. Then, the sufficient conditions are acquired to ensure the system is strictly (Γ1,Γ2,Γ3)-σ-dissipative exponentially stable by using the integral inequalities. Furthermore, the gains of the fuzzy controller can be expressed concretely through a skillful matrix decoupling method. At last, the effectiveness of the approach is illustrated via three examples.

Investigation and Application of Magnetic Properties of Ultra-Thin Grain-Oriented Silicon Steel Sheets under Multi-Physical Field Coupling.

Nowadays, energy shortages and environmental pollution have received a lot of attention, which makes the electrification of transportation systems an inevitable trend. As the core part of an electrical driving system, the electrical machine faces the extreme challenge of keeping high power density and high efficiency output under complex workin g conditions. The development and research of new soft magnetic materials has an important impact to solve the current bottleneck problems of electrical machines. In this paper, the variation trend of magnetic properties of ultra-thin grain-oriented silicon steel electrical steel (GOES) under thermal-mechanical-electric-magnetic fields is studied, and the possibility of its application in motors is explored. The magnetic properties of grain-oriented silicon steel samples under different conditions were measured by the Epstein frame method and self-built multi-physical field device. It is verified that the magnetic properties of grain-oriented silicon steel selected within 30° magnetization deviation angle are better than non-grain-oriented silicon steel. The magnetic properties of the same ultra-thin grain-oriented silicon steel as ordinary non-oriented silicon steel deteriorate with the increase in frequency. Different from conventional non-grain-oriented silicon steel, its magnetic properties will deteriorate with the increase in temperature. Under the stress of 30 Mpa, the magnetic properties of the grain-oriented silicon steel are the best; under the coupling of multiple physical fields, the change trend of magnetic properties of grain-oriented silicon steel is similar to that of single physical field, but the specific quantitative values are different. Furthermore, the application of grain-oriented silicon steel in interior permanent magnet synchronous motor (IPM) for electric vehicles is explored. Through a precise oriented silicon steel motor model, it is proved that the magnetic flux density of stator teeth increases by 2.2%, the electromagnetic torque of motor increases by 2.18%, and the peak efficiency increases by 1% after using grain-oriented silicon steel. In this paper, through the investigation of the characteristics of grain-oriented silicon steel, it is preliminarily verified that grain-oriented silicon steel has a great application prospect in the drive motor (IPM) of electric vehicles, and it is an effective means to break the bottleneck of current motor design.

Dissipative Asynchronous T-S Fuzzy Control For Singular Semi-Markovian Jump Systems.

This article addresses the problems of the dissipative asynchronous Takagi-Sugeno-Kong fuzzy control for a kind of singular semi-Markov jump system. An adjustable quantized approach is presented to deal with the uncertainties, nonlinear disturbance, actuator faults, and time-varying delay of the system. To deal with the problem of the nonsynchronous between system modes and controller modes, an asynchronous method is utilized. Then, a novel asynchronous sliding-mode controller is designed with an output measurement quantizer that is adaptive to the actuator faults and has good performance in practical applications. By solving the linear matrix inequalities, the sufficient conditions are obtained to guarantee the closed system stochastically admissible and strictly (Q,R,S)-α- dissipative and ensure the reachability of the sliding-mode surface. Finally, two numerical examples and comparisons are provided to illustrate the effectiveness and the priority of the proposed technique.

Finite-time H∞ synchronization for complex dynamical networks with time-varying delays based on adaptive control.

This paper investigates the problem of finite-time H∞ synchronization (H∞FTS) for complex dynamical networks (CDNs) with time-varying delays(TVDs) and unknown internal coupling matrices. External disturbances are also considered into this model. By applying the adaptive control theory, this paper presents the adaptive control method to solve the H∞FTS of CDNs with external disturbances and TVDs. Some criteria are obtained by utilizing appropriate adaptive controllers and devising a special Lyapunov-Krasovskii function (LKF), which ensure the H∞FTS of CDNs based on passivity theory. Finally, using some effective mathematical techniques, comparative numerical example and Chua's circuit system are used to explain the advantages and applicability of the results and approaches.

Renewable fatty acid ester production in Clostridium.

Bioproduction of renewable chemicals is considered as an urgent solution for fossil energy crisis. However, despite tremendous efforts, it is still challenging to generate microbial strains that can produce target biochemical to high levels. Here, we report an example of biosynthesis of high-value and easy-recoverable derivatives built upon natural microbial pathways, leading to improvement in bioproduction efficiency. By leveraging pathways in solventogenic clostridia for co-producing acyl-CoAs, acids and alcohols as precursors, through rational screening for host strains and enzymes, systematic metabolic engineering-including elimination of putative prophages, we develop strains that can produce 20.3 g/L butyl acetate and 1.6 g/L butyl butyrate. Techno-economic analysis results suggest the economic competitiveness of our developed bioprocess. Our principles of selecting the most appropriate host for specific bioproduction and engineering microbial chassis to produce high-value and easy-separable end products may be applicable to other bioprocesses.

Finite-time non-fragile extended dissipative control for T-S fuzzy system via augmented Lyapunov-Krasovskii functional.

The problem of non-fragile control for T-S fuzzy systems with parameter uncertainties is investigated in this paper. The focus is to construct an augmented Lyapunov-Krasovskii functional(LKF), single integral terms are processed by the method of an improved reciprocally convex inequality and integration by parts, which is derived to a new ht-depended stability criteria that finite-time bounded with extended dissipative for the closed-loop system. Furthermore, by using the linear matrix inequalities(LMIs), we can get the desired gain matrices of T-S fuzzy system. It is worth noting that these condition can derive to less conservative results than those existing approaches. And numerical examples are used to demonstrate the feasibility and superiority of the results.

Non-fragile sampled-date dissipative analysis for uncertain T–S fuzzy time delay system with actuator saturation.

In this paper, non-fragile fuzzy sampled-data control is used to analyze the dissipation of uncertain time-varying delay T–S fuzzy system under actuator saturation. First, this paper builds a novel augmented Lyapunov–Krasovskii functional that is more flexible. It involves complete information about the relevant sampled-data patterns. Second, the use of Wirtinger-based integral inequality and Newton–Leibniz formulas yields less conservative results. Next, we discuss the sufficient conditions of the dissipative performance for T–S model, then use the linear matrix inequality (LMI) to give the non-fragile fuzzy sampled-data controller with actuator saturation. Finally, the routine examples show that the advanced approach is effective and feasible and has certain advantages.

Non-fragile synchronization of complex dynamical networks with hybrid delays and stochastic disturbance via sampled-data control.

This paper focuses on the global synchronization issue for a class of the complex dynamical networks (CDNs) with hybrid delays and stochastic disturbance. The hybrid delays consider two forms: discrete-time coupling delays and distributed coupling delays. The non-fragile sampled-data control protocol, which is allowed to norm-bounded uncertainty, is considered for the first time in this paper. Next, by applying a new augmented Lyapunov-Krasovskii functional (LKF), with the aid of the convex combination method and the stochastic analysis technique, a less conservative condition is derived to ensure that the considered CDNs can achieve the global synchronization with hybrid delays and stochastic disturbance under a non-fragile sampled-data control strategy. Finally, there exists three simulation examples to verify the effectiveness and advantages of the analytical results.

Finite-time non-fragile H∞ sampled-data control for uncertain T-S fuzzy system with time-varying delay and nonlinear perturbation subject to Markovian jump.

This paper focuses on studying the finite-time non-fragile H∞ sampled-data control of uncertain T-S fuzzy time-varying delay system with nonlinear perturbation and Markovian jump parameters. We first construct a different Lyapunov-Krasovskii functional that plays a key role to fully capture the available characteristics of sampling period. Second, based on the Lyapunov-Krasovskii functional approach, free weighting matrix method and a novel efficient inequality technique, less conservative sufficient conditions are established, which make stochastic fuzzy system achieve finite-time boundedness and finite-time H∞ boundedness with an optimized performance. Then, the desired multiplicative non-fragile sampled-data control gains can be obtained by solving the linear matrix inequalities. Finally, three numerical examples are given to illustrate the effectiveness of the proposed method.

Finite-time extended dissipative control for fuzzy systems with nonlinear perturbations via sampled-data and quantized controller.

This paper investigates the problem of finite-time extended dissipative control for T-S fuzzy time-varying delay systems with nonlinear perturbations via sampled-data and quantized controller. The definition of finite-time bounded mixed extended dissipative of fuzzy systems is first proposed. Based on the constructed Lyapunov-Krasovskii functional(LKF) and Peng-Parks integral inequality, some sufficient conditions are obtained in the form of linear matrix inequalities(LMIs), which are less conservative than other papers. By combining the input delay approach and dynamic quantizer, the sampled-data and quantized controller is designed to guarantee that the T-S fuzzy system is finite-time bounded mixed extended dissipative. Finally, some numerical examples and practical examples are presented to verify the feasibility and effectiveness of the proposed methods.

Comparative Genomic and Genetic Functional Analysis of Industrial L-Leucine- and L-Valine-Producing Corynebacterium glutamicum Strains.

Corynebacterium glutamicum is an excellent platform for the production of amino acids, and is widely used in the fermentation industry. Most industrial strains are traditionally obtained by repeated processes of random mutation and selection, but the genotype of these strains is often unclear owing to the absence of genomic information. As such, it is difficult to improve the growth and amino acid production of these strains via metabolic engineering. In this study, we generated a complete genome map of an industrial L-valine-producing strain, C. glutamicum XV. In order to establish the relationship between genotypes and physiological characteristics, a comparative genomic analysis was performed to explore the core genome, structural variations, and gene mutations referring to an industrial L-leucine-producing strain, C. glutamicum CP, and the widely used C. glutamicum ATCC 13032. The results indicate that a 36,349 bp repeat sequence in the CP genome contained an additional copy each of lrp and brnFE genes, which benefited the export of L-leucine. However, in XV, the kgd and panB genes were disrupted by nucleotide insertion, which increase the availability of precursors to synthesize L-valine. Moreover, the specific amino acid substitutions in key enzymes increased their activities. Additionally, a novel strategy is proposed to remodel central carbon metabolism and reduce pyruvate consumption without having a negative impact on cell growth by introducing the CP-derived mutant H+/citrate symporter. These results further our understanding regarding the metabolic networks in these strains and help to elucidate the influence of different genotypes on these processes.

Identification and application of a growth-regulated promoter for improving L-valine production in Corynebacterium glutamicum.

BACKGROUND: Promoters are commonly used to regulate the expression of specific target genes or operons. Although a series of promoters have been developed in Corynebacterium glutamicum, more precise and unique expression patterns are needed that the current selection of promoters cannot produce. RNA-Seq technology is a powerful tool for helping us to screen out promoters with expected transcriptional strengths. RESULTS: The promoter PCP_2836 of an aldehyde dehydrogenase coding gene from Corynebacterium glutamicum CP was identified via RNA-seq and RT-PCR as a growth-regulated promoter. Comparing with the strong constitutive promoter Ptuf, the transcriptional strength of PCP_2836 showed a significant decrease that from about 75 to 8% in the stationary phase. By replacing the native promoters of the aceE and gltA genes with PCP_2836 in the C. glutamicum ATCC 13032-derived L-valine-producing strain AN02, the relative transcriptional levels of the aceE and gltA genes decreased from 1.2 and 1.1 to 0.35 and 0.3, and the activity of their translation products decreased to 43% and 35%, respectively. After 28 h flask fermentation, the final cell density of the obtained strains, GRaceE and GRgltA, exhibited a 7-10% decrease. However, L-valine production increased by 23.9% and 27.3%, and the yield of substrate to product increased 43.8% and 62.5%, respectively. In addition, in the stationary phase, the intracellular citrate levels in GRaceE and GRgltA decreased to 27.0% and 33.6% of AN02, and their intracellular oxaloacetate levels increased to 2.7 and 3.0 times that of AN02, respectively. CONCLUSIONS: The PCP_2836 promoter displayed a significant difference on its transcriptional strength in different cell growth phases. With using PCP_2836 to replace the native promoters of aceE and gltA genes, both the transcriptional levels of the aceE and gltA genes and the activity of their translation products demonstrated a significant decrease in the stationary phase. Thus, the availability of pyruvate was significantly increased for the synthesis of L-valine without any apparent irreversible negative impacts on cell growth. Use of this promoter can enhance the selectivity and control of gene expression and could serve as a useful research tool for metabolic engineering.

Robust observer-based passive control for uncertain singular time-delay systems subject to actuator saturation.

This paper investigates the problem of robust observer-based passive control for uncertain singular time-delay system subject to actuator saturation. A polytopic approach is used to describe the saturation behavior. First, by constructing Lyapunov-Krasovskii functional, a less conservative sufficient condition is obtained which guarantees that the closed-loop system is regular, impulse free, stable and robust strictly passive. Then, with this condition, the design method of state feedback controller and the observer are given by solving linear matrix inequalities. In addition, a domain of attraction in which the admissible initial states are ensured to converge asymptotically to the origin is solved as a convex optimization problem. Finally, some simulations are provided to demonstrate the effectiveness and superiority of the proposed method.

Complete genome sequence of Corynebacterium glutamicum CP, a Chinese l-leucine producing strain.

Here, we report the complete genome sequence of Corynebacterium glutamicum CP, an industrial l-leucine producing strain in China. The whole genome consists of a circular chromosome and a plasmid. The comparative genomics analysis shows that there are many mutations in the key enzyme coding genes relevant to l-leucine biosynthesis compared to C. glutamicum ATCC 13032.

[Effects of overexpression of key enzyme genes on guanosine accumulation in Bacillus amyloliquefaciens].

OBJECTIVE: To study the effects of overexpression of key enzyme genes (prs, purF and guaB) on guanosine production in Bacillus amyloliquefaciens TA208. METHODS: The prs, purF, guaB and prs-purF genes were inserted into constructed expression plasmid PBE43. All these constructed plasmids were electroporated into B. amyloliquefaciens TA208. The transcriptional level of various genes in the resulting strains was tested by real-time quantitative PCR. The activity of inosine 5'-monophosphate dehydrogenase in the resulting strains was detected. Finally, cell growth, glucose consumption and guanosine production of 4 engineering strains along with control strain were examined. RESULTS: The transcriptional analysis showed that overexpression of prs, purF and guaB gene accompanied by their own transcription level up-regulated. Overexpression of prs or purF genes alone slightly down-regulated the transcriptional level of purine operon, but overexpression of guaB gene independently did not disturb the transcription of prs gene and purine operon. Enzyme activity analysis showed that overexpression of prs or purF gene did not change the activity of inosine 5'-monophosphate dehydrogenase and its activity increased by 126% through overexpression of guaB gene. Finally, by fermentation flask test, we found that overexpression of prs and purF gene alone could not promote guanosine accumulation. However, overexpression of guaB gene resulted in an increase in the production of guanosine, which was 20.7% higher than the control strain. The guanosine concentration and the conversion ratio from glucose to guanosine in the host strain containing co-expression plasmid were 14.4% and 6.8% higher than the control strain. CONCLUSION: Overexpression of guaB gene could enhance the guanosine yield in the culture broth. However, for prs and purF gene, only co-expression of them could lead to a significant improvement of guanosine production in B. amyloliquefaciens. It should provide a valuable insight into the construction of industrially important strains for guanosine production by metabolic engineering.