Cristian Radu

Combining OPAC and lidar

The properties of aerosol particles are highly variable, both in time and space. This refers to the number density, the microphysical properties (size distribution, refractive index, effective radius), and to the height distribution. In most cases the actual properties are not known. Using lidar data together with models can help improve the knowledge regarding the particulate atmospheric constituents which affect local radiative forcing, the radiation balance of the earth, and thus climate. This paper presents an attempt to integrate elastic backscatter lidar data in OPAC software package in order to find the most realistic aerosol vertical distribution and their optical and microphysical characteristics. The necessity to reduce the variability of naturally occurring aerosols to typical cases, but without neglecting possible fluctuations, is achieved in OPAC by the use of a dataset of typical internally mixed aerosol components. In addition, any mixtures of the basic components can be used to calculate the overall optical parameters. Experimental or modeled meteorological profiles (temperature, pressure, relative humidity) in complementary to experimental lidar data are used to calculate the solutions of lidar equation that fits, in an iterative manner, to the output of the model. Two type of uncertainties are diminished in this way: first, the modeled profiles of lidar ratio are used in lidar data processing instead of a constant value; second, aerosol height profiles are no longer being assumed in the model, but directly measured. This procedure was applied to synthetic lidar signals in order to test its advantages and limitation.

Spatial optical solitons in fotonic crystals (1D) with cubic nonlinearity

The study of dynamics of spatial solitons in nonlinear and unidimesional fotonic crystals, with a periodical and nonlinear fotonic network which is generated by Dirac function is presented. Are analysed comparisons and differences which appear in development of periodical models describes by nonlinear Schrödinger equation. Also, is developed theory of couple models for periodical modulation of refractive index. Fudamental theory of spatial solitons are based to obtain discrete nonlinear Schrödinger equation with analyze of stationary solutions on discrete models.

An Er:YAG blood sampling skin puncher

Generally, the beam distribution in the tissue in interaction with a pulsed laser is defined by the optical properties (effective scattering and absorption coefficient). A special Er:YAG device used for blood sampling without any pain is presented. Our device emitting on 2940 nm has a special function. It can give four energy levels for four types of skin. At 3000 nm there is an absorption peak in water, and the absorption in tissue is intense and the vaporization is immediate and superficial without surrounding damages. Additionally, the very short duration of the pulse (a few hundred microseconds) avoids the phenomenon of thermal diffusion.

IMPACTS OF ANTHROPOGENIC ACTIVITIES IN BACAU AREA UPON HEAVY METALS CONCENTRATION ON BISTRITA RIVER SIDES

The main objective of the current research is to determine the content of heavy metals from the Bistrita river banks, respectively upstream of Bacau city, Romania, in Bogdan Voda area, and downstream of Bacau city. Because of their bio-accumulation tendency heavy metals can generate a negative impact on soil, as well as on certain physiological and biochemical indicators of plants and animals metabolism. The selection of sampling points (upstream and downstream of Bacau city) took into consideration the areas where the pollution sources are located and where the sediment layer is thick, having the granulosity level less than 63 m. We found that the Maximum Allowable Concentrations (MAC) were not exceeded in the case of cadmium, chrome, lead and mercury in the soil for sampling points upstream of Bacau city, in Bogdan-Voda area. The same situation was observed in the case of arsenic in sampling points upstream and downstream of Bacau city. Exceeding values recorded in the sampling point upstream of Bacau city, in Bogdan-Voda area (for nickel and copper) and downstream of Bacau city (for cadmium, nickel, chrome, copper, zinc, lead, mercury) resulted from discharged wastewaters and improper storage of municipal waste.

A special laser device for dielectric breakdown generation used in ophthalmology

To solve some microsurgical procedures in the anterior and posterior chambers using the photo disruptive effect, a special Nd:YAG nanosecond laser device is presented. The Nd:YAG laser is q-switched (Cr4+:YAG). The laser beam is expanded. After expansion, the laser beam is passed through a circular variable filter which is rotated by a processor, allowing energy to be set at any value in the range of 0.5-10 mJ. Two infrared LED-phototransistor pairs are used to position the filter. The laser beam is focused by the objective at 150 microns behind the object plane to avoid the damage of the Intraocular Lens.

Four energy levels device for skin punching

Generally, the beam distribution in the tissue in interaction with a pulsed laser is defined by optical properties (effective scattering and absorption coefficient). In 2900 nm range, the effective scattering coefficient is much smaller than the absorption coefficient. An Er:YAG skin puncher is presented. Thermal action of a laser beam can be described as one of three types: hyperthermia, coagulation and volatilization, depending on the degree and the duration of tissue heating. We are interested in the volatilization process that means a loss of material. The various constituents of the tissue disappear in smoke at above 1000C in a relatively short time of around one tenth of a second. At the edges of the volatilization zone there is a region of coagulation necrosis. In presented case of an Er:YAG laser operating in a free generation mode, the mechanical effects can result from explosive vaporization. When the exposure time of the laser is lower than the characteristic time of the thermal diffusion in the tissue, it produces a thermal containment with an accumulation of heat without diffusion and an explosive vaporization of the target. The Er:YAG laser device has the pulse length of about 160 microseconds and four emitted energy levels. This device is used to punch the skin for blood sampling for different kinds of analysis. The front panel of the device has four keys to select the desired energy according to the skin type.

Simulator for the configuration of a lidar installation

The LIDAR virtual system represents an interactive software instrument able to optimize the configuration process of a LIDAR installation, but also to represent a virtual environment for modeling studies of the (for) atmospherical processes. With a virtual LIDAR is chooses an optimal configuration before the LIDAR installaiton construction, which is very important if (it takes) the high costs of a functional LIDAR installation are taken into account. The paper describes the analytic model used to characterize the emission, propagation and reception processes, and a description concerning the system components programming and the graphic interface realization of a LIDAR virtual system.