Effects of milling conditions on hydrogen storage properties of graphite

Two milling modes (shearing and impact) were applied to investigate the hydrogen storage properties of graphite. It was found that the shearing mode leads to 0.613 wt.% hydrogen absorbed in graphite, while impact mode leads to 2.718 wt.%. X-ray diffraction was used to investigate the structure of the as-milled and subsequent annealed samples. Differential scanning calorimetry was used to study thermally induced transformations in the as-milled samples. Infrared spectrometry was carried out to investigate the interaction between carbon and hydrogen atoms. Results are compared and discussed in conjunction with Laser desorption time-of-flight mass spectrometry results obtained earlier.     

CdS Nanoplates Modification as a Platform for Synthesis of Blue-Emitting Nanoparticles

In this paper, the study of surface modification of two-dimensional (2D), non-luminescent CdS nanoplates (NPLs) by thiol-containing ligands is presented. We show that a process of twophase transfers with appropriate ligand exchange transforms non-luminescent NPLs into spherical CdS nanoparticles (NPs) exhibiting a blue photoluminescence with exceptionally high quantum yield ~90%. In the process, transfer from inorganic solvent to water is performed, with appropriately selected ligand molecules and pH values (forward phase transfer), which produces NPs with modified size and shape. Then, in reverse phase transfer, NPs are transferred back to toluene due to surface modification by combined Cd (OL)₂ and Cd (Ac)₂. As a result, spherical NPs are formed (average diameter between 4 and 6 nm) with PL QY as high as 90%. This is unique for core only CdS NPs without inorganic shell.     

Modeling of Flow System Dynamics

This paper presents non-linear and linear models of flow system of laboratory stand (semi-industrial scale) with pressurized fluidized bed boiler. The non-linear model belongs to the class of lumped parameter models. The linear model was obtained experimentally using a novel method for design of control systems in industrial plants - MIKOZ. This study has connection with comparison of various methods of mathematical modeling of flow systems frequently encountered in power equipment.     

Control strategy of the hybrid drive for vehicle mounted aerial work platform

The development process i.e. assumptions, construction, simulations and analysis of a control strategy for the hybrid drive of the vehicle mounted aerial work platform is presented in the paper. Particular attention is paid to the development of the control system strategy ensuring appropriate energy recuperation by making use of energy stored in the electrochemical form. The control strategy is built up around the concept of bi-level hierarchic control system. The elevation control of the aerial work platform is assumed as the primary goal of the control system. The secondary goal of the control system is formulated in terms of tracking and keeping the charging level of the rechargeable electrochemical accumulator in predefined limits. A control system simulation model is developed in Matlab-Simulink environment. Exemplary results of control system simulations are shown on the example of a hydraulic power unit driving aerial work platform mounted on special vehicle MONTRAKS.     

NURBS to Avoid Boundary Orientation Poses in Serial Manipulators

A procedure to build NURBS motion interpolants to avoid boundary orientation poses for serial manipulator architectures is presented. As an example, the PUMA architecture was used. The procedure, which emerged from B‐spline curves theory, enables a local change of the NURBS motion interpolant. The change may be introduced in any arbitrary neighborhood of the chosen boundary orientation pose. Therefore, when tracking a trajectory, one may change NURBS motion interpolant value at any time instant, leaving its remaining values untouched. Recommendation for further research pertains to exploiting the flexibility of NURBS applied to robot kinematics. © 2003 Wiley Periodicals, Inc.     

Drainage and economic utilization of methane from coal seams in the Jastrzebie mining-field

The paper presents the resources and present status of coal-seam methane from the mining field of JSW S.A., as well as trends in its application both in JSW S.A. plants and elsewhere. For the period 1999–2001, the dynamics of growth of methane utilization are shown. Perspectives of methane drainage are considered, with regard to both work and the realization of restructuring programs in the mining industry. Demand and supply of methane are discussed, taking into account real and potential opportunities. An assessment was made of the emissions to the atmosphere both of methane and of other pollutants. An evaluation of the influence exerted by these measures on the performance of cogeneration of heat and electricity has been prepared. Several projects in progress are described, namely the increase of gas-firing in existing boiler installations, investment projects referring to the installation of gas engines for cogeneration of heat and electricity, utilization of the distribution network for the maximum utilization of gas and the designs of power-generation systems (using methane) for air conditioning in the mines.     

Amino acids as substrates for preparation of monomers with imide rings

The reaction of pyromellitic anhydride PMDA with some amino acids lead to monomers, which were used to synthesize new polymers. Application to glycine, D ,L -alanine and β-alanine gave three bis-acid chlorides. These are able to condense with glycols and diamines to yield a series of new copolyimides. Amino acids of two carboxylic groups D ,L -glutamic acid and D ,L -aspartic acid gave, in reaction with PMDA, two similar dianhydrides (4) and (5). However, the condensation with aromatic amines lead to two different compounds. It was proved that, under the conditions studied, formation of hexa-membered imide rings was impossible while penta-membered imides formed without difficulty. Thermogravimetric analyses of these polymers were also carried out.     

Bounds on the average message reassembly time in a packet data network

In this paper we compute lower and upper bounds on the mean reassembly time of a multipacket message under general assumptions. We show that the approximation which is known from the literature is in fact a lower bound. Simulation results give some hints on how to make a better approximation, according to the given bounds.