NFPA 921 advises the use of a systematic approach to fire investigation that is best embodied by the scientific method. The scientific method includes the steps of collecting data, analyzing that data, developing a hypothesis, and then testing that hypothesis. The final step of this process, testing the hypothesis, can be done either physically or analytically. In some cases, a physical test may be conducted to confirm or falsify some aspect of the hypothesis. However, in many cases creating a physical test may be difficult or even practically impossible. It is these cases, and others, where analytic testing using computer simulations may be helpful to the fire investigator.
This is the first blog in a series on integrating new technologies into the process of forensic investigations. Documenting the scene of an incident accurately, efficiently, and safely is a key step in every investigation. Busy roadways and unstable structures present hazards to the investigator during the investigation process. The use of remote sensors can reduce these risks and provide data that otherwise could not safely be obtained.
Many people just take for granted that something is just going to work, and in many cases assume that it will work forever. One such device that does not get enough attention is the Ground Fault Circuit Interrupter (GFCI). Simply put, a GFCI is a protective device that compares the current flowing on the hot and neutral wires of the circuit and will "trip" to disconnect power to the circuit if a small imbalance of current is detected. The imbalance of current is an indication of a dangerous alternate path for the current to flow from a damaged line cord or a fault inside an appliance and constitutes a shock hazard to a person.
The feasibility of two-beam speckle interferometry for the study of time-varying mechanical deformation of diffusely reflecting bodies is demonstrated. A sequence of speckle patterns produced by a vibrating cantilever beam was recorded photographically by means of a high-speed camera. These speckle photographs were subsequently digitized using a CCD camera for input into an image processing computer. By gray-level subtraction of carefully registered pairs of speckle images, fringes corresponding to the relative surface displacements were obtained. A sequence of these fringe patterns was reconstructed to obtain the time-history of deformation. These are compared with time-frozen (strobed) patterns for the same body.
A gray level transformation is presented to simulate the interferometric process. The transformation uses properties of sinusoidal functions to produce rapidly varying intensities from those with nearly zero gradients. The transformation when used in conjunction with optical techniques, such as holographic interferometry, has the effect of increasing the optical sensitivity and producing a large number of fringes where otherwise only a fraction of a fringe would be observed. This technique is ideal for holographic analysis of deformations in microscopic regions.
An In-Vehicle Data Acquisition/Monitoring Device (Data Logger) has been developed to be used for evaluating the performance of alternators during vehicle operation. It can be linked to other controllers and electronic devices for exchange of information through the use of a serial communication port. By utilizing a microcontroller, eight analog and three TTL level signals are measured and recorded in non-volatile EEPROM memory devices. The system measures temperatures of critical components, system voltage and rotational speed.
Case Synopsis - A family wanted to add a self-contained heater for their home living room for use upon the loss of in-home AC (Alternating Current) power. They went to a nearby Home & Building Supply store to select and purchase a heater. The store salesman recommended a kerosene heater, which could provide independent heat upon a loss of power. The salesman recommended a kerosene heater rated at 23,000 BTU/Hour, and as a feature of the heater sale, he assembled the heater and provided brief operating instructions on its use.
When I was a boy, playing in the sandbox or building with blocks, I dreamed of building cities. I feel fortunate to be in a profession which allows me to fulfill that dream. To enjoy your job is a more important measure of success than the amount of money in your bank account. My favorite definition of success is borrowed from Ann Landers:
Too frequently an attorney will begin to seek a potential expert witness only after having done considerable initial work. Often there is a last minute rush to locate and select specialized technical assistance. These approaches can have expensive consequences. Alternatively, securing a suitable expert early in the litigation process offers the following advantages for the retaining attorney: