Determination of Harmonics of Converter Current and/or Voltage Waveforms (New Method for Fourier Coefficient Calculations), Part II: Fourier Coefficients of Nonhomogeneous Functions

The method used in Part I for the determination of Fourier coefficients of homogeneous functions is generalized here for nonhomogeneous functions. A number of examples from the field of power converter and inverter circuits are presented. Such special cases as harmonics of oscillations at the moments of valve's ignitions and extinctions are analyzed here.     

Power Efficient Video Multipath Transmission over Wireless Multimedia Sensor Networks

This paper proposes a power efficient multipath video packet scheduling scheme for minimum video distortion transmission (optimised Video QoS) over wireless multimedia sensor networks. The transmission of video packets over multiple paths in a wireless sensor network improves the aggregate data rate of the network and minimizes the traffic load handled by each node. However, due to the lossy behavior of the wireless channel the aggregate transmission rate cannot always support the requested video source data rate. In such cases a packet scheduling algorithm is applied that can selectively drop combinations of video packets prior to transmission to adapt the source requirements to the channel capacity. The scheduling algorithm selects the less important video packets to drop using a recursive distortion prediction model. This model predicts accurately the resulting video distortion in case of isolated errors, burst of errors and errors separated by a lag. Two scheduling algorithms are proposed in this paper. The Baseline scheme is a simplified scheduler that can only decide upon which packet can be dropped prior to transmission based on the packet’s impact on the video distortion. This algorithm is compared against the Power aware packet scheduling that is an extension of the Baseline capable of estimating the power that will be consumed by each node in every available path depending on its traffic load, during the transmission. The proposed Power aware packet scheduling is able to identify the available paths connecting the video source to the receiver and schedule the packet transmission among the selected paths according to the perceived video QoS (Peak Signal to Noise Ratio—PSNR) and the energy efficiency of the participating wireless video sensor nodes, by dropping packets if necessary based on the distortion prediction model. The simulation results indicate that the proposed Power aware video packet scheduling can achieve energy efficiency in the wireless multimedia sensor network by minimizing the power dissipation across all nodes, while the perceived video quality is kept to very high levels even at extreme network conditions (many sensor nodes dropped due to power consumption and high background noise in the channel).     

Ertüchtigung eines Gründerzeithauses für den Lastfall Erdbeben

Infolge einer Umwidmung eines ehemaligen Geschäftslokals in einen Kindergarten verlangte die Baubehörde eine Verbesserung der Horizontalaussteifung des in den 60er Jahren geschwächten Gründerzeitgebäudes. Die Erdbebensicherheit von Gründerzeithäusern wird erläutert. Die erfolgte Ertüchtigung des Gebäudes wird beschrieben. Strengthening of a Gründerzeit building for the load case earthquake. As a consequence of a rededication of a former salesroom to a kindergarten the building authority demanded a strengthening of the horizontal stability of the Gründerzeit building, which was weakened by removing walls in the 1960s. The earthquake resistance of Gründerzeit buildings is explained. The strengthening of the building is described.     

Oxygen-Generating Cryogels Restore T Cell Mediated Cytotoxicity in Hypoxic Tumors

Solid tumors are protected from antitumor immune responses due to their hypoxic microenvironments. Weakening hypoxia-driven immunosuppression by hyperoxic breathing of 60% oxygen has shown to be effective in unleashing antitumor immune cells against solid tumors. However, efficacy of systemic oxygenation is limited against solid tumors outside of lungs and has been associated with unwanted side effects. As a result, it is essential to develop targeted oxygenation alternatives to weaken tumor hypoxia as novel approaches to restore immune responses against cancer. Herein, injectable oxygen-generating cryogels (O₂-cryogels) to reverse tumor-induced hypoxia are reported. These macroporous biomaterials are designed to locally deliver oxygen, inhibit the expression of hypoxia-inducible genes in hypoxic melanoma cells, and reduce the accumulation of immunosuppressive extracellular adenosine. The data show that O₂-cryogels enhance T cell-mediated secretion of cytotoxic proteins, restoring the killing ability of tumor-specific cytotoxic T lymphocytes, both in vitro and in vivo. In summary, O₂-cryogels provide a unique and safe platform to supply oxygen as a coadjuvant in hypoxic tumors and have the potential to improve cancer immunotherapies.     

An integrated cyber security risk management framework and risk predication for the critical infrastructure protection

Neural Computing and Applications - Cyber security risk management plays an important role for today’s businesses due to the rapidly changing threat landscape and the existence of evolving...     

Nature of high reactivity of metal/solid oxidizer nanocomposites prepared by mechanoactivation: a review

In this review, the regularities of formation, structure and high reactivity of two types of energetic metal/solid oxidizer nanocomposites (Al(Mg)/X (X = MoO₃, (–C₂F₄–) _n )) prepared by mechanoactivation are examined. One reason for the high reactivity is an increase in contact surface between the components occurring after mechanoactivation. Two methods for determination of area of contact surface S _C between the components are used, and the values of S _C for all the systems are estimated. Considerable attention is paid to the role of highly reactive defects (grain sizes, dislocations and stacking faults, paramagnetic centers, “weakly bound” oxygen in MoO₃, etc.), formed in the components under mechanical stress. For the Me/MeO₃ systems, the formation of point defects in the oxide is an important factor. It was found that, after mechanoactivation, the evolution of O₂ from MoO₃ occurs at 230–450 °C. It is argued that this process is associated with the thermal destruction of “weak” Mo–O bonds in the “bridge” oxygen. It was suggested that the formation of defect structure in MoO₃ and increasing of the oxygen mobility under heating give rise to a low-temperature peak in DSC curves and initiated self-ignition on the fuel–air mixture. For composites Mg/MoO₃, self-ignition occurs at temperature 100 °C lower than that for Al/MoO₃: The decreasing of temperature can be connected with larger S _C in the first system. In the Mg/(–C₂F₄–) _n system, the reactions of magnesium defects with (–C₂F₄–) _n are accompanied by a weak heat evolution, too low to initiate ignition. In this case, the reaction is initiated by the thermal depolymerization of (–C₂F₄–) _n , while a high values of S _C provide a complete conversion. In the case of shock-wave initiation, defects in the components play only a minor role in the conversion, whereas the value of S _C remains to be highly important.     

Spatial distribution of doubly scattered polarized laser radiation in the focal plane of a lidar receiver

Depolarization lidars are widely used to study clouds and aerosols because of their ability to discriminate between spherical particles and particles of irregular shape. Depolarization of cloud backscattered radiation can be caused also by multiple scattering events. One of the ways to gain information about particle parameters in the presence of strong multiple scattering is the measurement of radial and azimuthal dependence of the polarization patterns in the focal plane of receiver. We present an algorithm for the calculation of corresponding polarized patterns in the frame of double scattering approximation. Computations are performed for various receiver field of views, for different parameters of the scattering geometry, e.g., cloud base and sounding depth, as well as for different values of cloud particle size and refractive index. As the spatial distribution of cross-polarized radiation is of cross shape and rotated at 45 degrees with respect to laser polarization, the use of a properly oriented cross-shaped mask in the receiver focal plane allows the removal of a significant portion of the depolarized component of the backscattered radiation produced by double scattering. This has been verified experimentally based on cloud depolarization measurements performed at different orientations of the cross-shaped mask. Results obtained from measurements are in agreement with model predictions.     

HyperTree: a structural approach to web authoring

The expansion of the World Wide Web (WWW) has created an increasing need for tools capable of supporting WWW authors in composing documents using the HyperText Markup Language (HTML). Currently, most web authors use tools which are basically ordinary text editors and have additional features to facilitate the easy and correct use of HTML tags. This approach places the burden on the web author to design and then create the entire web site in a top-down fashion, without any explicit support for the structural design of the site. In this paper we discuss an alternative structural approach to Web authoring, which is based on the use of the HyperTree hypermedia system as the central authoring tool. The advantages of using HyperTree are two-dimensional. Firstly, web authors can manage a web site as a single complete hypermedia database. For example, HyperTree provides facilities like the automatic creation of indices and the discovery of link inconsistencies. Additionally, it organizes the web pages in an easy to understand hierarchy without using any HTML directly. Secondly, web end-users can benefit from the use of HyperTree, since seeking information in structured web sites is generally less disorientating and develops fewer cognitive overheads. ©1997 John Wiley & Sons, Ltd.     

Multiscale modeling reveals poisoning mechanisms of MgO-supported Au clusters in CO oxidation

Catalyst deactivation mechanisms on MgO-supported Au(6) clusters are studied for the CO oxidation reaction via first-principle kinetic Monte Carlo simulations and shown to depend on support vacancies. In defect-poor MgO or in the presence of a Mg vacancy, O(2) does not bind to the clusters and the catalyst is poisoned by CO. On Au clusters interacting with O vacancies of the support, O(2) can be chemisorbed and transient activity is observed. In this case, an unexpected catalyst "breathing" mechanism (restructuring) leads to carbonate formation and catalyst deactivation, rationalizing several experimental observations. Our study underscores the importance of the cluster's charge state and dynamics on catalytic activity.