Fractal dimension of the bone marrow in metastatic lesions

We previously reported that the distribution of the cells in normal bone marrow is fractal and self-similar. The purpose of this study was to determine whether the same is true in metastatic tumors. Thirty-two bone marrow biopsy sections (3 to 5 microm thick) of 28 patients were used to measure the fractal dimensions of the metastatic tumor cells' distribution. Microscopic images were obtained and were used for the fractal measurements. In the two-dimensional images, the fractal dimensions were 1.98 +/- 0.02 (95% +/- 5% cellularity), suggesting a compact nonfractal structure. The dimensions, however, were 1.72 +/- 0.1 (56% +/- 11% cellularity) for the normal components, with a P-value of <.0001 that is in agreement with our previous study. These results suggest that loss of the fractal structure in the metastatic lesions may be attributable to loss or suppression of the regulatory mechanisms maintaining the fractal morphogenesis of the bone marrow. This report provides a novel objective approach in the study of pathophysiology of the bone marrow disorders.     

Cylinder Liner Surface Analysis During SI Engine Break-In

Surface texture of an engine cylinder liner at the top-ring reversal point was observed by using Scanning Electron Microscopy (SEM) and optical microscopy. Experiments were conducted on a single-cylinder spark ignition engine over the engine break-in period. The surface texture of the cylinder liner was observed before and after the break-in test. The changes of surface texture and the wear mechanisms during the engine break-in were analyzed. The primary wear mechanisms were found to be abrasion and plastic deformation.     

Deficiencies of design-spectrum compatible accelerograms

Frequency-domain scaled, design spectrum compatible acceleration time histories (DSCTH) are widely used in the analysis and design of special structures, particularly seismic-isolated buildings. At the first glance, it seems that DSCTH records furnish earthquake resistant designers with a consistency and compatibility bridge between the two very different worlds of elastic and inelastic response. Closer examination reveals, however, that there are significant potential problems associated with indiscriminate use of DSCTH records in seismic design.     

Selection of earthquake records for seismic design of tall buildings

One of the most difficult questions that the designer of tall earthquake resistant buildings must address is the determination of the critical earthquake. This is the earthquake ground motion that will drive the structure being designed to its critical response. This paper seeks to help the seismic design engineer address this difficult problem by identification of the severity and damage potential of critical components obtained from a database of more than 5000 records of strong earthquake ground motion. These records virtually represent all the available North American and Hawaiian records written by ground-level instruments for the period of 1933–1992. Elastic and inelastic response and energy spectra are studied. Spectral data are sorted in terms of the mean value of the response parameter in bracketed bands of the fundamental period.     

Engine Fault Analysis: Part II?Parameter Estimation Approach

The general fault analysis problem can be divided into two parts: fault detection and diagnosis (location). Fourier series, autocorrelation, and other techniques have been used for fault detection. However, these approaches cannot be utilized for locating the faults. In this paper a methodology is presented to locate faulty cylinder(s). The procedure involves the development of a mathematical model of the engine dynamics. This model takes into consideration the cylinder gas pressure, engine inertia, and load. The resultant torque is computed by using parameter estimation techniques. The parameter estimation technique employed can determine time-varying parameters without prior knowledge of the structure of the parameter. In the problem at hand, this is an important requirement. The resultant torque is the net of the cylinder gas torque and the frictional torque. The model and the estimation procedure have been verified by performing tests on a single-cylinder engine. A discriminant function has been defined to classify the performance of each cylinder. Our results indicate that the amplitude of the resultant torque can be used to identify the faulty cylinder(s). We have verified this approach by tests and studies on a six-cylinder engine. In our experiments we have studied cases involving one or two faulty cylinders.