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This paper develops a novel method for moving force identification (MFI) called preconditioned least square QR-factorization (PLSQR) method. The algorithm seeks to reduce the impact of identification errors caused by unknown noise. The biaxial moving forces travel on a simply supported bridge at three different speeds is used to generate numerical simulations to assess the effectiveness and applicability of the algorithm. Results indicate that the method is more robust towards ill-posed problem and has higher identification precision than the conventional time domain method (TDM). In addition, the robustness and ill-posed immunity of PLSQR are directly affected by two kinds of regularization parameters, namely, number of iterations j and regularization matrix L. Compared with the standard form of least square QR-factorization (LSQR), i.e., the regularization matrix L being the identity matrix In, the PLSQR with the optimal number of iterations j and regularization matrix L has many advantages on MFI and it is more suitable for field trials due to better adaptability with type of sensors and number of sensors.

This paper develops a modified preconditioned conjugate gradient (M-PCG) method for moving force identification (MFI) by improving the conjugate gradient (CG) and preconditioned conjugate gradient (PCG) methods with a modified Gram-Schmidt algorithm. The method aims to obtain more accurate and more efficient identification results from the responses of bridge deck caused by vehicles passing by, which are known to be sensitive to ill-posed problems that exist in the inverse problem. A simply supported beam model with biaxial time-varying forces is used to generate numerical simulations with various analysis scenarios to assess the effectiveness of the method. Evaluation results show that regularization matrix L and number of iterations j are very important influence factors to identification accuracy and noise immunity of M-PCG. Compared with the conventional counterpart SVD embedded in the time domain method (TDM) and the standard form of CG, the M-PCG with proper regularization matrix has many advantages such as better adaptability and more robust to ill-posed problems. More importantly, it is shown that the average optimal numbers of iterations of M-PCG can be reduced by more than 70% compared with PCG and this apparently makes M-PCG a preferred choice for field MFI applications.

Background: Emergence of resistant organisms is alarmingly high all over the world. Irrational and inappropriate prescription of antimicrobials is the major contributing factor for developing drug resistance in addition to poor patient compliance. It is the high time to create awareness of antimicrobial resistance among physicians and patients. Encouraging physicians/surgeons to undergo training programmes on infectious disease control periodically would be beneficial to combat the resistant organisms, so called super bugs. Objectives: To assess the pattern of antimicrobial usage in a tertiary care hospital, to determine whether antimicrobials are prescribed judiciously. Methods: A retrospective study was conducted to determine the current antimicrobial prescribing practices at Tagore Medical College Hospital. A randomised sample of 100 inpatient case sheets of General Medicine, OBG, General Surgery, Paediatrics, Chest Medicine, Skin, and ENT from Medical Records Department was analysed with respect to oral and parenteral (iv) administration of antimicrobials. Results: In this study, 53% were males and 47% were females. Majority of patients were middle aged (17-60yrs). A total of 16 antimicrobials were prescribed for 100 inpatients. The most frequently used were Metronidazole and Ciprofloxacin. Duration of treatment was minimum 3 days, maximum of 13 days and mean duration was 5.5 days. The common route by which antimicrobials were administered was Parenteral as the patients were inpatients. The Parenteral (iv) drugs were Metronidazole (52%), Ciprofloxacin (42%), Cefotaxime (27%), Amikacin (7%), Ceftriaxone (7%). Among 100 prescriptions, 63% were empirical prescriptions, 12% were directed and 25% were targeted prescriptions. Conclusions: The most frequently used antimicrobials were Metronidazole and Ciprofloxacin and the condition for which the antimicrobials were commonly used was acute gastroenteritis. The proportion of targeted prescriptions was low compared to em

Background: Emergence of resistant organisms is alarmingly high all over the world. Irrational and inappropriate prescription of antimicrobials is the major contributing factor for developing drug resistance in addition to poor patient compliance. It is the high time to create awareness of antimicrobial resistance among physicians and patients. Encouraging physicians/surgeons to undergo training programmes on infectious disease control periodically would be beneficial to combat the resistant organisms, so called super bugs. Objectives: To assess the pattern of antimicrobial usage in a tertiary care hospital, to determine whether antimicrobials are prescribed judiciously. Methods: A retrospective study was conducted to determine the current antimicrobial prescribing practices at Tagore Medical College Hospital. A randomised sample of 100 inpatient case sheets of General Medicine, OBG, General Surgery, Paediatrics, Chest Medicine, Skin, and ENT from Medical Records Department was analysed with respect to oral and parenteral (iv) administration of antimicrobials. Results: In this study, 53% were males and 47% were females. Majority of patients were middle aged (17-60yrs). A total of 16 antimicrobials were prescribed for 100 inpatients. The most frequently used were Metronidazole and Ciprofloxacin. Duration of treatment was minimum 3 days, maximum of 13 days and mean duration was 5.5 days. The common route by which antimicrobials were administered was Parenteral as the patients were inpatients. The Parenteral (iv) drugs were Metronidazole (52%), Ciprofloxacin (42%), Cefotaxime (27%), Amikacin (7%), Ceftriaxone (7%). Among 100 prescriptions, 63% were empirical prescriptions, 12% were directed and 25% were targeted prescriptions. Conclusions: The most frequently used antimicrobials were Metronidazole and Ciprofloxacin and the condition for which the antimicrobials were commonly used was acute gastroenteritis. The proportion of targeted prescriptions was low compared to em

Background: Emergence of resistant organisms is alarmingly high all over the world. Irrational and inappropriate prescription of antimicrobials is the major contributing factor for developing drug resistance in addition to poor patient compliance. It is the high time to create awareness of antimicrobial resistance among physicians and patients. Encouraging physicians/surgeons to undergo training programmes on infectious disease control periodically would be beneficial to combat the resistant organisms, so called super bugs. Objectives: To assess the pattern of antimicrobial usage in a tertiary care hospital, to determine whether antimicrobials are prescribed judiciously. Methods: A retrospective study was conducted to determine the current antimicrobial prescribing practices at Tagore Medical College Hospital. A randomised sample of 100 inpatient case sheets of General Medicine, OBG, General Surgery, Paediatrics, Chest Medicine, Skin, and ENT from Medical Records Department was analysed with respect to oral and parenteral (iv) administration of antimicrobials. Results: In this study, 53% were males and 47% were females. Majority of patients were middle aged (17-60yrs). A total of 16 antimicrobials were prescribed for 100 inpatients. The most frequently used were Metronidazole and Ciprofloxacin. Duration of treatment was minimum 3 days, maximum of 13 days and mean duration was 5.5 days. The common route by which antimicrobials were administered was Parenteral as the patients were inpatients. The Parenteral (iv) drugs were Metronidazole (52%), Ciprofloxacin (42%), Cefotaxime (27%), Amikacin (7%), Ceftriaxone (7%). Among 100 prescriptions, 63% were empirical prescriptions, 12% were directed and 25% were targeted prescriptions. Conclusions: The most frequently used antimicrobials were Metronidazole and Ciprofloxacin and the condition for which the antimicrobials were commonly used was acute gastroenteritis. The proportion of targeted prescriptions was low compared to em

The moving vehicle loads on a bridge deck is one of the most important live loads of bridges. They should be understood, monitored and controlled before the bridge design as well as when the bridge is open for traffic. A MOM-based algorithm (MOMA) is proposed for identifying the time-varying moving vehicle loads from the responses of bridge deck in this paper. It aims at an acceptable solution to the ill-conditioning problem that often exists in the inverse problem of moving force identification. The moving vehicle loads are described as a combination of whole basis functions, such as orthogonal Legendre polynomials or Fourier series, and further estimated by solving the new system equations developed with the basis functions. A number of responses have been combined, some numerical simulations on single axle, two axle and multiple-axle loads, being either constant or time-varying, have been carried out and compared with the existing time domain method (TDM) in this paper. The illustrated results show that the MOMA has higher identification accuracy and robust noise immunity as well as producing an acceptable solution to ill-conditioning cases to some extent when it is used to identify the moving force from bridge responses.

An improved time domain method (ITDM) is proposed for identification of moving vehicle loads on a bridge based on both moments method and theory of moving force identification. The moving vehicle loads are expressed in terms of orthogonal Legendre polynomials and then estimated from the bridge bending moment responses caused by the moving vehicles on the bridge. By using the measured bending moment responses of a bridge model made in laboratory, the authors investigate effect of various parameters on the ITDM. These parameters include Legendre basis function number, mode number, measured stations and CPU executive time of the ITDM. Further, the ITDM is compared with the existing time domain method (TDM). Experimental study results show that the ITDM has good properties almost same as those of the TDM, but it can save the identification CPU time as well as it has a better flexibility than the TDM. This is beneficial to real time analysis of moving force online identification.

An improved time domain method (ITDM) is proposed for moving force identification from dynamic responses of bridges, which aims at an acceptable solution to the ill-conditioning problem that often exists in inverse problems such as moving force identification. Based on the method of moments and the theory of moving force identification, the moving forces were described as a combination of whole basis functions, i.e. orthogonal Legendre polynomials, and further were estimated by solving the new system equations developed with the basis functions. In the cases of a number of responses combination, numerical simulations for both two axles constant loads and two time-varying loads of a vehicle have been carried out and compared with the existed time domain method (TDM). The illustrated results show that for the problem of the identification of moving force from bridge responses, ITDM has higher accuracy and robuster noise immunity, and to some extent, ITDM can offer an acceptable solution to the ill-conditioning problem.

A method is presented to identify moving forces on a continuous bridge. The bridge is modeled as a continuous supported Bernoulli-Euler beam and the boundary value problem of the beam is solved to get the exact mode shape functions of vibrating beam with inner supports. The bending moment responses are used to study the inverse problem in identifying moving forces on a bridge. The SVD (singular value decomposition) is used in the solution to study the inverse problem. Two time varying forces moving over the bridge are simulated to evaluate the method. White noise is added to simulated bending moment responses to study the effect of noise in moving forces identification problem for different numbers and arrangements of sensors. Results obtained from simulation study show that the method is effective in identifying moving forces and acceptable results can be obtained.

Based on the Euler-Beam theory, the moving vehicle loads on bridges were identified from the response of bridges using the Time Domain MethQd (TDM) and Frequency-Time Domain Method (FTDM). This paper aims to investigate the effect of various parameters on the two methods. These parameters include mode number, sampling frequency, vehicle speed, locations and numbers of measured stations. Assessment results show that the vehicle-bridge model in laboratory is successful. Both methods are effective and acceptable with higher accuracy, and the TDM is the preferred in-situ method with good feasibility and robustness.

Most of the identification methods are eventually converted to a linear algebraic equation set. Different ways to solve the equation set will result in solutions with completely different levels of accuracy. Bused on the frequency-time domain method (FTDM), the moving vehicle-axle loads are identified from the measured responses induced by the vehides crossing a bridge. The focus is on evaluation of two solutions i.e.,direct calculation of pscudo inverse (PI) and calculation of pseudo inverse via the singular value decomposition (SVD) technique to the equation set estahlished in the FTDM. The effects of various parameters on identified results also are discussed. Assessment results show that the SVD technique can obviously improve identification accuracy as compared to the Pl solution.

Estimation (filtering) theory for dynamical sys tems is reviewed. Emphasis is on time varying systems and nonstationary stochastic processes. The basic ideas for linear systems are presented in an intuitive manner using time domain tech niques and the state variable concept. Both continuous and discrete time systems are dis cussed. A control problem and the principle of least squares curve fitting are related to the basic estimation problem. In addition to the presentation of fundamental principles for linear systems, brief discussions on a wide variety of related subjects are included in an appendix.

The time domain scattering for an isolated dipole and for n uncoupled dipoles is investigated theoretically. The basic approach used is the Fourier transform of the frequency-dependent scattering function. The following qualitative information may be obtained from an investigation of the output waveform: (1) The approximate length of the scatterer (from the resonant frequency of the scattered waveform), (2) an indication of the Q of the scatterer (from the envelope of the output waveform) and (3) the relative separation of n scatterers. (Author), Supersedes Rept. no. Scientific-B-2 dated 8 Jul 68, AD-674 068.