681 research outputs found

    An extension of the identification algorithm for feedback active control of incomplete measured systems

    Get PDF
    In a previous paper [1], the identification algorithm is presented for feedback active controlled systems. However, this method can only be applied to complete measured systems. The aim of this paper is to present a combination of the identification algorithm and the modal superposition method to control the incomplete measured systems. The system response is expanded by modal eigenfunction technique. The external excitation acting on some first modes is identified with a time delay and with a small error depending on the sensor locations. Then the control forces will be generated to balance the identified excitations. A numerical simulation is applied to an eight story building subjected to base acceleration

    On a feedback-feedforward identification control algorithm for feedback active controlled structures

    Get PDF
    Linear quadratic regulator (LQR) is an effective method of feedback active control theory. However, the LQR control is not truly optimal because it is only a feedback algorithm, i.e. the external excitation term is ignored in the optimal equation. In a previous paper [1], the identification algorithm is presented for feedback active controlled systems to identify the excitation from the structural response measured. The aim of this paper is to propose a feedback-feedforward control algorithm using the identified excitation to improve the classical LQR control. A numerical simulation is applied to an eight story building subjected to base acceleration and controlled by active mass damper system

    Evaluation Of Allelopathic Potential Of Cissus sicyoides Against the Growth Of Echinochloa Crus-Galli And Some Tested Plants

    Get PDF
    Many plant species in nature exert significant allelopathic potential as part of the defense mechanism system, many among their secondary metabolites (allelochemicals), including mineral constituents, which are responsible for the suppression of weeds and enhancing crop yield when directly incorporated into paddy fields. Cissus sicyoides is considered a high-potential allelopathic plant because of its invasion in nature and detected allelochemicals from the plant parts in some studies. The objective of this research was to exploit the allelopathic properties of C.sicyoides against paddy weeds and some indicator plants under laboratory bioassays and greenhouse conditions. The results demonstrated that C. sicyoides had significant inhibition on E. crus-galli, tested plants, and other paddy weeds. In the laboratory conditions, the extracts from C.sicyoides leaves inhibited the growth of Echinochloa crus-galli by 54.3%. The powders from C.sicyoides leaves inhibited the emergence of paddy weeds by approximately 100.0%. In the greenhouse conditions, the powders from C.sicyoides leaves by adding after 3 and 13 days inhibited the growth of E. crus-galli and the emergence of paddy weeds by 64.4%. Remarkably, negligible harmful effects on rice growth were observed. The findings of the study may provide useful information for the exploitation of this plant species to effectively control weeds in the rice fields for sustainable agriculture production

    IDENTIFICATION OF A BACTERIOCIN PRODUCING BY LACTOCOCCUS LACTIS SUBSP. LACTIS PD14

    Get PDF
    The strain Lactococcus PD14 isolated from cow’s fresh milk was identified as Lactococcus lactis subsp. lactis. The bacteriocin produced by PD14  was isolated and purified by absorption-desorption method described and then this bacteriocin was purified by solid-phase extraction-SPE and HPLC method with column C18. The result of tricine- SDS-PAGE indicated the molecular weight of bacteriocin was about 3.5 kDa, the same as nisin. The prenisin encoding gene was cloned and sequenced successfully for PD14. The nis gene of the strain PD14 was 99 % homology with nisA and nisZ while 98 % with nisF, 97 % with nisQ. The deduced amino acid sequence of prenisin was determined, which had minor difference from published sequence of nisA in one amino acid. At the position aminoacid -18, prenisin of PD14 had valine while  the known prenisin A had phenylalanine. The matured nisin of PD14 was completely similar to the known amino acid sequence of nisA. Thus, the strain Lactococcus lactis subsp. lactis. PD14 produced a bacteriocin which was identified as nisin A

    Dynamics of the informal sector : evidence from Vietnam

    Get PDF
    Findings imply that the Vietnamese government should provide more assistance to weak firms and release regulation interventions to promote formalisation. Firms moving from formal to informal conditions are often either weak businesses that have no potential to expand or strong enterprises which want to escape from government regulations. This first-ever study creates an informality index to capture the nature of informality using the Multiple Correspondence Analysis (MCA). By using Cluster Analysis to segment firms and investigate factors associated with each cluster, the paper contributes enormously to studies focusing on the high heterogeneity of informal enterprises in Vietnam

    Genetic Diversity and Population Structure of Canarium tramdenum Dai and Yakovl. in Northern Vietnam

    Get PDF
    Canarium tramdenum occurs naturally in subtropical and tropical regions of Indochina and China. The wood is used for making high quality furniture and the fruit and leaves are used in traditional medicine. However, a lack of information on genetic diversity and population structure has handicapped the genetic conservation and domestication of this high-value species. This study evaluated genetic variation within and among four C. tramdenum populations. Sixty individuals were collected from four natural populations in Vietnam in the provinces of Ninhbinh, Bacgiang, Nghean, and Backan. Genetic diversity and genetic structure were determined using 20 ISSR markers. A total of 192 DNA fragments with sizes ranging from 110 bp to 3,000 bp were detected, of which 154 segments (80.2%) were polymorphic and 38 segments (19.8%) were monomorphic. The ISSR data indicated a moderate degree of genetic diversity for the species (h = 0.252). The four populations were separated into three genetic clusters with low levels of genetic distance between them. AMOVA result showed that most (78%) of the genetic variation was within the populations. The moderate to high genetic diversity of C. tramdenum and the low genetic differentiation among populations suggested that all existing natural populations in the particular regions needed to be preserved to protect the genetic diversity of this species

    Antioxidant and in vitro antidiabetic activities of Peperomia pellucida (L.) Kunth extract

    Get PDF
    Peperomia pellucida (L.) is commonly used as a herbal plant. Its effectiveness in treating inflammatory diseases, digestive disorders, and cancer in tropical and subtropical countries was introduced, especially in field of folk medicine. However, this plant species has not been studied widely in Vietnam, especially for its biological activities. This study was done to determine the antioxidant capacity of P. pellucida by using in vitro and in vivo methods, as well as its inhibitory ability to α-amylase enzyme activity. The total polyphenolic and flavonoid contents of P. pellucida extract were reported to be 359.91±0.77 mg GAE/g and 200.28±1.23 mg QE/g extract, respectively. The results showed the in vitro antioxidant activity of P. pellucida extract in four methods, including DPPH, and ABTS.+, RP and TAC, had EC50 values of 730.34 μg/mL, 84.33 μg/mL, 95.28 μg/mL, respectively, and Abs0.5 value of 114.73 μg/mL. Under H2O2-induced oxidative stress, fruit flies that were raised in the feed medium supplemented with a concentration of 1 mg/mL of P. pellucida extract showed their average survival time, 50% survival time, and 10% survival time at 1.6 times, 1.8 times, and 1.62 times, respectively, higher than those of the control treatment. The ability to inhibit the α-amylase activity in P. pellucida extract was determined with an EC50 value of 115.32±2.65 μg/mL compared with the commercial drug of 18.67±0, 01 μg/mL. The research results showed that P. pellucida is a potential species in the study of natural compounds with antioxidant and antidiabetic activities
    corecore