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1.
We show the results in Chalishajar [Controllability of mixed Volterra-Fredholm-type integro-differential systems in Banach space, J. Franklin Inst. 344(1) (2007) 12-21] and Chang and Chalishajar [Controllability of mixed Volterra-Fredholm type integro-differential systems in Banach space, J. Franklin Inst., doi:10.1016/j.jfranklin.2008.02.002] are only valid for ordinary differential control systems. As a result the examples provided cannot be recovered as applications of the abstract results.  相似文献   

2.
In [S. Basu, Multi-dimensional filter banks and wavelets—a system theoretic perspective, J. Franklin Inst. 335B(8) (1998) 1367-1409], the problems of constructing and parameterizing multi-dimensional (MD) filter banks (FB) and wavelets were studied extensively, especially in the situation of two-dimensional (2D) and quincunx-downsampled systems. Finding the other filter complementary to a given 2D filter for quincunx sampling and linear phase perfect reconstruction (LPPR) system is based on the fact that the construction is possible if and only if the polyphase components of the given filter do not share any common zero. The construction is elaborated in another book chapter [S. Basu, Multidimensional signals, circuits and systems, in: K. Galkowski, J. Wood (Eds.), On the Structure of Linear Phase Perfect Reconstruction Quincunx Filter Banks, Taylor & Francis, London, 2001, pp. 193-208 (Chapter 10)] by the same author. This approach further relies on the fact that the resultant of the polyphase components is monomial. In this comment, we show that both above mentioned facts are not necessarily true for the quincunx FB as well as for general MD FB.  相似文献   

3.
The method of identifying first order plus time delay transfer function model proposed for unstable systems by Ananth and Chidambaram [Closed loop identification to transfer function model for unstable systems, J. Franklin Inst. 336 (1999) 1055-1061] is modified to avoid the stability problems [Cheres, Parameter estimation of an unstable system with a PID controller in a closed loop configuration, J. Franklin Inst., 2005, accepted for publication] of the method. Two modifications are proposed. In the first modification of the method, the under-determined algebraic equations problem is converted into an optimization problem for calculation of the three parameters of the first order plus time delay (FOPTD) model. A simple method is given for the initial guess values of the model parameters. In the second approach, from the definition of Laplace transform of the output response, a third equation is formulated. The resulted three equations, in terms of the three parameters of the transfer function model, are then numerically solved. Simulation results are given for the second order plus time delay transfer function considered by Cheres 2005 [Parameter estimation of an unstable system with a PID controller in a closed loop configuration, J. Franklin Inst., 2005, accepted for publication]. The responses of the identified models with the same PID controllers are compared with that of the actual system. PID controllers are designed based on the identified models. The closed loop responses of the controllers on the original system are evaluated and compared. The present methods give better control performances.  相似文献   

4.
This paper gives a general review of the Theory of Nonlinear Systems. In 1960, the author presented a paper “Theory of Nonlinear Control” at the First IFAC Congress at Moscow. Professor Norbert Wiener, who attended this Congress, drew attention to his work on the synthesis and analysis of nonlinear systems in terms of Hermitian polynomials in the Laguerre coefficients of the past of the input.Wiener's original idea was to use white noise as a probe on any nonlinear system. Applying this input to a Laguerre network gives u1, u2,…, us, and then to a Hermite polynomial generator gives V(α)'s. Applying the same input to the actual nonlinear system gives output c(t). Putting c(t) and V(α)'s through a product averaging device, we get c(t)V(α) = Aα2лs2, where the upper bar denotes time average and Aα's can be considered as characteristic coefficients of the nonlinear system. A desired output z(itt) may replace c(itt) to get a new set of Aα's.The Volterra functional method suggested by Wiener in 1942 has been greatlydeveloped from 1955 to the present. The method involves a multi-dimensional convolution integral with multi- dimensional kernels. The associated multi-dimensional transforms are given by Y.H. Ku and A.A. Wolf (J. Franklin Inst., Vol. 281, pp. 9–26, 1966). Wiener extended the Volterra functionals by forming an orthogonal set of functionals known as G-functionals, using Gaussian white noise as input. Volterra kernels and Wiener kernels can be correlated and form the characteristic functions of nonlinear systems.From an extension of the linear system to the nonlinear system, the input-output crosscorrelation φxy can be shown to be equal to the convolution of system impulse response h1 with the autocorrelation φxx. Using the white noise as input, where its power density spectrum is a constant, say, A, the crosscorrelation is given by φxy(σ) = Ah1(σ), while the autocorrelation is φxx(τ) = Au(τ). This extension forms the basis of an optimum method for nonlinear system identification. Measurement of kernels can be made through proper circuitry.Parallel to the Volterra series and the Wiener series, another series based on Taylor-Cauchy transforms developed since 1959 are given for comparison. The Taylor-Cauchy transform method can be applied in the analysis of simultaneous nonlinear systems. It is noted that the Volterra functional method and the Taylor-Cauchy transform method give identical final results.A selected Bibliography is appended not only to include other aspects of nonlinear system theory but also to show the wide application of nonlinear system characterization and identification to problems in biology, ecology, physiology, cybernetics, control theory, socio- economic systems, etc.  相似文献   

5.
Having obtained anomalous results in an attempt to continue the simulation study of moth-wasp interaction in Auslander, Oster and Huffaker (J. Franklin Inst. 297, 345-375), attention was centered on the role of spatial heterogeneity in an environment with the moth (Anagasta kühniella) alone. Because of the probable presence of chaotic components in the population behavior (random appearing behavior that is actually caused by deterministic influences), a statistically-based parameter sensitivity and parameter identification method was used. By defining a binary performance criterion that measured the ability of a model with a specific set of parameters to maintain a stable population, the importance of spatial heterogeneity was confirmed. In addition, the use of Monte-Carlo type simulation studies, combined with a binary performance criterion, was demonstrated to be effective for parameter identification and/or parameter sensitivity determination of at least some systems with chaotic or nearly chaotic behavior.  相似文献   

6.
Nonlinear system identification and prediction is a complex task, and often non-parametric models such as neural networks are used in place of intricate mathematics. To that cause, recently an improved approach to nonlinear system identification using neural networks was presented in Gupta and Sinha (J. Franklin Inst. 336 (1999) 721). Therein a learning algorithm was proposed in which both the slope of the activation function at a neuron, β, and the learning rate, η, were made adaptive. The proposed algorithm assumes that η and β are independent variables. Here, we show that the slope and the learning rate are not independent in a general dynamical neural nétwork, and this should be taken into account when designing a learning algorithm. Further, relationships between η and β are developed which helps reduce the number of degrees of freedom and computational complexity in an optimisation task of training a fully adaptive neural network. Simulation results based on Gupta and Sinha (1999) and the proposed approach support the analysis.  相似文献   

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8.
BackgroundFreeze-drying is known as one of the best methods to preserve bacterial strains. Protectant is the key factor affecting the survival rate of freeze-dried strains. In addition, salinity, bacterial suspension concentration, drying time, and other factors can also affect the survival rate of strains to varying degrees. At present, there are relatively few studies on freeze-drying preservation of marine bacteria. In the present study, we performed the freeze-drying protectant screening and optimized the preservation conditions for Pseudoalteromonas nigrifaciens, which is widely distributed in marine environment. The protective effects of the screened protectants were verified by 18 other marine bacterial strains.ResultsThe results indicated that the combination of 5.0% (w/v) lactose, 5.0% (w/v) mannitol, 5.0% (w/v) trehalose, 10.0% (w/v) skim milk powder, 0.5% (w/v) ascorbic acid and 0.5% (w/v) gelatin was the best choice for the preservation of P. nigrifaciens. The suggested salinity and concentration of initial cell suspension were 10 g/L NaCl and 1.0 × 109 CFU/mL, respectively. Furthermore, stationary-phase cells were the best choice for the freeze-drying process. The highest survival rate of P. nigrifaciens reached 52.8% when using 5–10% (w/v) skim milk as rehydration medium. Moreover, the other 18 marine strains belonging to Pseudoalteromonas, Vibrio, Photobacterium, Planomicrobium, Edwardsiella, Enterococcus, Bacillus, and Saccharomyces were freeze-dried under the abovementioned conditions. Their survival rates were 2.3–95.1%.ConclusionCollectively, our results supported that the protectant mixture and parameters were beneficial for lyophilization of marine bacteria.How to cite: Zhang Z, Yu Y, Wang Y, et al. Development of new protocol for freeze-drying preservation of Pseudoalteromonas nigrifaciens and its protective effect on other marine bacteria. Electron J Biotechnol 2020;44. https://doi.org/10.1016/j.ejbt.2019.12.006.  相似文献   

9.
The Franklin Institute, Philadelphia, Pennsylvania, awards the 2011 Benjamin Franklin Medal in Chemistry to Professor Kyriacos C. Nicolaou for his extraordinary contributions to chemistry, biology, and medicine through the advancement of the art of synthesis as exemplified by the elegant total syntheses of some of nature's most complex biologically active molecules. Nicolaou is recognized as a world leader in the field of total synthesis for his work in chemical synthesis and chemical biology. His total syntheses are legendary, distinguished for their elegance and practicality. Among his most celebrated achievements are the total syntheses of calicheamicin γ1I, Taxol®, brevetoxin B, vancomycin, and thiostrepton. The impact of his work transcends total synthesis, for it often leads to the discovery and invention of new synthetic strategies and technologies as well as biological tools and drug candidates, thereby facilitating discoveries in biology and medicine. Nicolaou's influence on science and society extends beyond his research discoveries. Through his didactic lectures and writings, he motivates and inspires students into the sciences and informs the public about the importance of science and education to society.  相似文献   

10.
The Franklin Institute, Philadelphia, Pennsylvania, awarded the 2002 Benjamin Franklin Medal in Life Sciences to Mary-Dell Chilton for her key discoveries and wide-ranging contributions in the development of the Agrobacterium tumefaciens Ti plasmid as a major vector system for plant genetic engineering.  相似文献   

11.
BackgroundThe heterologous expression of parasitic proteins is challenging because the sequence composition often differs significantly from host preferences. However, the production of such proteins is important because they are potential drug targets and can be screened for interactions with new lead compounds. Here we compared two expression systems for the production of an active recombinant aldehyde dehydrogenase (SmALDH_312) from Schistosoma mansoni, which causes the neglected tropical disease schistosomiasis.ResultsWe produced SmALDH_312 successfully in the bacterium Escherichia coli and in the baculovirus expression vector system (BEVS). Both versions of the recombinant protein were found to be active in vitro, but the BEVS-derived enzyme showed 3.7-fold higher specific activity and was selected for further characterization. We investigated the influence of Mg2+, Ca2+ and Mn2+, and found out that the specific activity of the enzyme increased 1.5-fold in the presence of 0.5 mM Mg2+. Finally, we characterized the kinetic properties of the enzyme using a design-of-experiment approach, revealing optimal activity at pH 7.6 and 41°C.ConclusionsAlthough, E. coli has many advantages, such as rapid expression, high yields and low costs, this system was outperformed by BEVS for the production of a schistosome ALDH. BEVS therefore provides an opportunity for the expression and subsequent evaluation of schistosome enzymes as drug targets.How to cite: Harnischfeger J, Beutler M, Salzig D, et al. Biochemical characterization of the recombinant schistosome tegumental protein SmALDH_312 produced in E. coli and baculovirus expression vector system. Electron J Biotechnol 2021;54. https://doi.org/10.1016/j.ejbt.2021.08.002  相似文献   

12.
BackgroundIn industrial yeasts, selection and breeding for resistance to multiple stresses is a focus of current research. The objective of this study was to investigate the tolerance to multiple stresses of Saccharomyces cerevisiae obtained through an adaptive laboratory evolution strategy involving a repeated liquid nitrogen freeze–thaw process coupled with multi-stress shock selection. We also assessed the related resistance mechanisms and very high-gravity (VHG) bioethanol production of this strain.ResultsElite S. cerevisiae strain YF10-5, exhibiting improved VHG fermentation capacity and stress resistance to osmotic pressure and ethanol, was isolated following ten consecutive rounds of liquid nitrogen freeze–thaw treatment followed by plate screening under osmotic and ethanol stress. The ethanol yield of YF10-5 was 16% higher than that of the parent strain during 35% (w/v) glucose fermentation. Furthermore, there was upregulation of three genes (HSP26, HSP30, and HSP104) encoding heat-shock proteins involved in the stress response, one gene (TPS1) involved in the synthesis of trehalose, and three genes (ADH1, HXK1, and PFK1) involved in ethanol metabolism and intracellular trehalose accumulation in YF10-5 yeast cells, indicating increased stress tolerance and fermentative capacity. YF10-5 also showed excellent fermentation performance during the simultaneous saccharification and fermentation of VHG sweet potato mash, producing 13.40% (w/v) ethanol, which corresponded to 93.95% of the theoretical ethanol yield.ConclusionsA multiple-stress-tolerant yeast clone was obtained using adaptive evolution by a freeze–thaw method coupled with stress shock selection. The selected robust yeast strain exhibits potential for bioethanol production through VHG fermentation.How to cite: Zhang Q, Jin Y, Fang Y, et al. Adaptive evolution and selection of stress-resistant Saccharomyces cerevisiae for very high gravity bioethanol fermentation. Electron J Biotechnol 2019;41. https://doi.org/10.1016/j.ejbt.2019.06.003  相似文献   

13.
This paper is concerned with the non-fragile dynamic output feedback control for uncertain T–S fuzzy systems with time-varying delay and randomly occurring gain variations (ROGVs). Considering the imperfect premise matching that the T–S fuzzy model and the fuzzy controller do not have the same membership function, the purpose is to enhance the robustness of the system and the flexibility of the controller design. By adjusting the free weight matrix in the concept of extended dissipative, H∞, L2−L∞, passive and (Q, S, R)-dissipative performance are solved in a unified framework. Stochastic phenomenon ROGVs is considered to describe the impact of the controller gain variations in the system, which is designed into two sequences of random variables and obey the Bernoulli distribution. Based on Lyapunov–Krasovskii functional (LKF) and integral inequality technique, some less conservative sufficient conditions are obtained to guarantee the close-loop system is asymptotically stable and extended dissipative. By solving the linear matrix inequalities (LMIs), a non-fragile dynamic output feedback controller can be developed. The advantage and effectiveness of the proposed design method can be illustrated by several numerical examples.  相似文献   

14.
Software users have different sets of personal values, such as benevolence, self-direction, and tradition. Among other factors, these personal values influence users’ emotions, preferences, motivations, and ways of performing tasks—and hence, information needs. Studies of user acceptance indicate that personal traits like values and related soft issues are important for the user’s approval of software. If a user’s dominant personal value were known, software could automatically show an interface variant which offers information and functionality that best matches his or her dominant value. A user’s dominant personal value is the one that most strongly influences his or her attitudes and behaviors. However, existing methods for measuring a user’s values are work intensive and/or interfere with the user’s privacy needs. If interface tailoring for very large groups of users is planned, value approximation has to be achieved on a large scale to assign individualized software to all users of the software. Our work focuses on approximating the dominant values of a user with less effort and less impact on privacy. Instead of probing for a user’s values directly, we explore the potential of approximating these values based on the user’s preferences for key tasks. Producing tailored versions of software is a separate topic not in the focus here. In this paper we rather describe a method to identify user values from task preferences and an empirical study of applying parts of this method. We are proposing the method in this paper for the first time except for a preliminary version orally presented at a workshop. The method consists of a research process and an application process. In the research process a researcher has to identify key tasks occurring in a context under investigation which have a relationship to personal values. These key tasks can be used in the application process to approximate the dominant values of new users in a similar context. In this empirical study we show that the research process of our method allows us to determine key tasks which approximate values in the shared context of nursing. The majority of the nurses were found to have one of the three following dominant values: benevolence, self-direction, or hedonism. Data confirmed common expectations: that nurses with the value of benevolence, when compared to all other nurses, had a higher preference for tasks which helped people immediately or improved their circumstances of the treatment. In relation to all other nurses, participants with self-direction disliked tasks which affected their personal freedom, and users with hedonism had a lower preference for tasks which involved physical work and preferred tasks which promised gratification. Our findings advance measurement of personal values in large user groups by asking questions with less privacy concern. However, the method requires substantial efforts during the initial research process to prepare such measurements. Future work includes replicating our method in other contexts and identifying value-dependent tasks for users with other values than the three values our empirical study mainly focused on.  相似文献   

15.
This paper is concerned with the network-based H∞ fuzzy filtering for non-linear systems with parameter uncertainties under a novel adaptive discrete event-triggered communication scheme (DETCS). Based on interval type-2 (IT2) Takagi–Sugeno (T–S) fuzzy model, the non-linear systems with parameter uncertainties are represented as a class of IT2 T–S fuzzy systems. In the design process, a novel adaptive DETCS is proposed to reduce the usage of system resources and adapt the variation of plant output, and a novel networked IT2 T–S fuzzy filter is applied to improve the flexibility of filter design. By employing the time-delay systems modeling method, the filtering-error-system is modeled as a class of interval time-varying delayed IT2 T–S fuzzy systems with asynchronously and imperfectly matched membership functions, and further conditionally expressed as a favorable form. Then, some relaxed stability criteria are established to determine that this class of delayed IT2 T–S fuzzy systems is asymptotically stable with a prescribed H∞ disturbance attenuation performance. Also, the co-design of parameter matrices of adaptive DETCS and filter is implemented. Finally, two numerical examples are provided to demonstrate the effectiveness of the proposed method.  相似文献   

16.
BackgroundThe effects of dietary nutrition on tail fat deposition and the correlation between production performance and the Hh signaling pathway and OXCT1 were investigated in fat-tailed sheep. Tan sheep were fed different nutritional diets and the variances in tail length, width, thickness and tail weight as well as the mRNA expression of fat-related genes (C/EBPα, FAS, LPL, and HSL) were determined in the tail fat of sheep at three different growth stages based on their body weight. Furthermore, the correlations between tail phenotypes and the Hedgehog (Hh) signaling pathway components (IHH, PTCH1, SMO, and GLI1) and OXCT1 were investigated.ResultsC/EBPα, FAS, LPL, and HSL were expressed with differences in tail fat of sheep fed different nutritional diets at three different growth stages. The results of the two-way ANOVA showed the significant effect of nutrition, stage, and interaction on gene expression, except the between C/EBPα and growth stage. C/EBPα, FAS, and LPL were considerably correlated with the tail phenotypes. Furthermore, the results of the correlation analysis demonstrated a close relationship between the tail phenotypes and Hh signaling pathway and OXCT1.ConclusionsThe present study demonstrated the gene-level role of dietary nutrition in promoting tail fat deposition and related tail fat-related genes. It provides a molecular basis by which nutritional balance and tail fat formation can be investigated and additional genes can be identified. The findings of the present study may help improve the production efficiency of fat-tailed sheep and identify crucial genes associated with tail fat deposition.How to cite: Zeng J, Zhou S, Yang Y, et al. Effect of dietary nutrition on tail fat deposition and evaluation of tail-related genes in fat-tailed sheep. Electron J Biotechnol 2020;46. https://doi.org/10.1016/j.ejbt.2020.05.004.  相似文献   

17.
1. The sensitometric characteristics of photographic plates exposed to hydrogen peroxide and developed are strikingly similar, both for time of exposures, time of development, and intensity i.e., concentration). Characteristic curves similar to H. and D. curves were obtained, including a period of “reversal.”2. A tentative theory of the action of hydrogen peroxide is suggested. It is supposed that the decomposition of peroxide is chemi-luminiscent, short wave-length radiation being afforded at the surface of the silver halide grain, and particularly at check the hypothesis that these nuclei consist of colloid silver.The authors desire to express their thanks to Mr. R. F. Quirk and Mr. E. Huberth for painstaking assistance in the experi- mental work, and to Miss Anber J. Benedict for making the pH measurements.  相似文献   

18.
In this paper, the exponential stabilization problem of uncertain T–S fuzzy systems with time-varying delay is emulated by fuzzy sampled-data H∞ control. Firstly, a novel suitable Lyapunov–Krasovskii function is constructed, which contains all the information about the sampling pattern. Secondly, a less conservative result is achieved by using an extended Jensen inequality, and purposefully using a compact free weighting matrix. In addition, according to the linear matrix inequality (LMI), some sampled-data H∞ exponential stability sufficient conditions and controller design of T–S fuzzy systems are established. Finally, effectiveness gives some illustrative examples may be used to display the value of the current proposed method as well as a significant improvement.  相似文献   

19.
BackgroundAgkistrodon acutus, a traditional Chinese medicine, clinically used in the treatment of rheumatism, tumor, and cardiovascular and cerebrovascular diseases. Due to the unique medicinal value and the difficulty of artificial breeding of Agkistrodon acutus, the supply of Agkistrodon acutus on the market exceeds the demand, and a large number of its adulterants are found on the market. In this study, the cytb gene sequences of Agkistrodon acutus and 9 snakes were compared and analyzed, specific primers were designed, and specific PCR methods were established to detect Agkistrodon acutus medicinal samples on the market.ResultsThis method was successfully applied to distinguish the snake from other adulterated species, and tested 18 Agkistrodon acutus samples randomly purchased from six cities. Twelve samples were counterfeit and six were genuine. The standard reference material of Agkistrodon acutus was cloned by molecular cloning and sequencing, and the gene sequence difference with other species was significant. It shows that the region could be used as the fingerprint region of the target species.ConclusionsThe proposed method can be used as a species-specific marker and can be highly distinguished from other adulterated snake species, which is helpful to effectively avoid the problem of false sale of Agkistrodon acutus.How to cite: Yingnuo L, Yanshuang W, Mingcheng Li, et al. Development of a species-specific PCR assay for authentication of Agkistrodon acutus based on mitochondrial cytochrome b gene. Electron J Biotechnol 2021;49. https://doi.org/10.1016/j.ejbt.2020.07.005  相似文献   

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