Relationships between accident investigations, risk analysis, and safety management

Several different approaches to achieve safety are in common use, and examples are accident investigations (AI), risk analysis (RA), and safety management systems (SMS). The meaning of these concepts and their practical applications vary quite a lot, which might cause confusion. A summary of definitions is presented. A general comparison is made of application areas and methodology. A proposal is made how to indicate parameters of variation. At one end of the scale there are organisations, which are highly organised in respect to safety. At the other end are small companies with informal safety routines. Although the three concepts differ in a number of respects, there are many links between them which is illustrated in a model. A number of relations have been described mainly concerned with more advanced organisations. Behind the practical safety work, there are varying sets of more or less explicit explanations and theories on safety and accident causation. Depending on the theory applied, the relations between approaches can be more or less clear and essential.     

Atomic-scale STM experiments on semiconductor surfaces: towards molecular nanomachines

The electronic or quantum control of individual molecules with the scanning tunnelling microscope offers exciting perspectives on operating molecular nanomachines. This implies the use of semiconductor surfaces rather than metallic surfaces which would rapidly quench the electronic excitations. We review recent results illustrating the state of the art and the main problems which need to be solved: the choice, design and properties of functionalized organic molecules on semiconductor surfaces; the control of the inelastic electronic channels through a single molecule; and the search for well-controlled atomic-scale wide-band-gap semiconductor surfaces.     

Do work technique and musculoskeletal symptoms differ between men and women performing the same type of work tasks?

Musculoskeletal disorders are more common among women than among men. When comparing the difference between men and women in the prevalence of musculoskeletal disorders, methodological problems arise as men and women seldom perform the same type of activities, neither at work nor at home.

The main objective of this cross-sectional case study was to compare work technique and self-reported musculoskeletal symptoms between men and women performing the same type of work tasks within a metal industry. Other factors, such as leisure activities, were also taken into consideration. Three data collection methods were used; questionnaire, interviews and systematic observations. The results from the observations revealed that women worked more frequently and during longer times with their hands above shoulder height than men. Working with hands above shoulder height is considered a risk factor for neck and shoulder disorders according to previous studies. Workplace design factors were probably a reason for differences in working technique between men and women. A higher proportion of women than men reported shoulder symptoms. Women spent more time on household activities than men, which indicates a higher total workload in paid and unpaid work.     

Skin color-based video segmentation under time-varying illumination

A novel approach for real-time skin segmentation in video sequences is described. The approach enables reliable skin segmentation despite wide variation in illumination during tracking. An explicit second order Markov model is used to predict evolution of the skin-color (HSV) histogram over time. Histograms are dynamically updated based on feedback from the current segmentation and predictions of the Markov model. The evolution of the skin-color distribution at each frame is parameterized by translation, scaling, and rotation in color space. Consequent changes in geometric parameterization of the distribution are propagated by warping and resampling the histogram. The parameters of the discrete-time dynamic Markov model are estimated using Maximum Likelihood Estimation and also evolve over time. The accuracy of the new dynamic skin color segmentation algorithm is compared to that obtained via a static color model. Segmentation accuracy is evaluated using labeled ground-truth video sequences taken from staged experiments and popular movies. An overall increase in segmentation accuracy of up to 24 percent is observed in 17 out of 21 test sequences. In all but one case, the skin-color classification rates for our system were higher, with background classification rates comparable to those of the static segmentation.     

Automatic writer identification using connected-component contours and edge-based features of uppercase Western script

In this paper, a new technique for offline writer identification is presented, using connected-component contours (COCOCOs or CO3s) in uppercase handwritten samples. In our model, the writer is considered to be characterized by a stochastic pattern generator, producing a family of connected components for the uppercase character set. Using a codebook of CO3s from an independent training set of 100 writers, the probability-density function (PDF) of CO3s was computed for an independent test set containing 150 unseen writers. Results revealed a high-sensitivity of the CO3 PDF for identifying individual writers on the basis of a single sentence of uppercase characters. The proposed automatic approach bridges the gap between image-statistics approaches on one end and manually measured allograph features of individual characters on the other end. Combining the CO3 PDF with an independent edge-based orientation and curvature PDF yielded very high correct identification rates.     

The study of control methods for the robotic testing system for human musculoskeletal joints

Biomechanical testing of human musculoskeletal joints not only requires qualified testing machines and devices, but also needs an excellent control method to obtain better experimental results. In this paper, we take the human functional spinal unit (FSU) as an example to study how to improve the performance of the robotic testing system. First, the mechanical characteristics of the FSU are described and the simplified model (a rigid body-spring system) for the specimen is given. Because the location of the center of rotation (COR) of the specimen affects the performance of the system, so a comprehensive analysis on the location of the COR is carried out. Furthermore, the performance of the robotic testing system can be also improved through the improvement of the control methods. Two control methods have been proposed, one is the improved hybrid control and the other is fuzzy logic control (FLC).     

Improving generalization capabilities of dynamic neural networks

This work addresses the problem of improving the generalization capabilities of continuous recurrent neural networks. The learning task is transformed into an optimal control framework in which the weights and the initial network state are treated as unknown controls. A new learning algorithm based on a variational formulation of Pontrayagin's maximum principle is proposed. Under reasonable assumptions, its convergence is discussed. Numerical examples are given that demonstrate an essential improvement of generalization capabilities after the learning process of a dynamic network.     

A sliding mode control proposal for open-loop unstable processes

This papers presents a sliding mode controller based on a first-order-plus-dead-time model of the process for controlling open-loop unstable systems. The proposed controller has a simple and fixed structure with a set of tuning equations as a function of the desired performance. Both linear and nonlinear models were used to study the controller performance by computer simulations.     

甘氨酸在无机氧化物表面吸附与热聚合机理研究

采用DTG、XRD、FTIR和in-situ DRIFT等手段对甘氨酸在SiO2和Al2O3表面的吸附和热聚合行为进行了研究.结果表明,在SiO2表面呈多层吸附,吸附量大,其聚合产物为环状二聚体DKP,SiO2对甘氨酸的吸附活化主要是通过表面≡Si-O-基团;而在Al2O3表面的吸附符合Langmuir吸附模型,吸附量小,吸附位主要是表面Lewis酸位(Al3+)和碱位(O2-),聚合产物为线式二聚体,高温下转化为环状二聚体DKP.