Uniform Distribution Of Radiation Research Articles

High-Efficiency Photovoltaic Equipment for Agriculture Power Supply

Developing an energy supply based on resources whose use does not spoil the noosphere and the creation of such energy supply of efficient equipment whose operation does not cause any damage to nature and man is an urgent task. The need for such an approach is especially relevant and noticeable in agriculture. This article presents the final results of complex studies of new PV devices and PV systems based on them. Considered in the article are the best solutions we propose to improve PV equipment and make it more attractive for agricultural consumers. The developed vertical and planar high-voltage multijunction silicon PV cells and PV modules on their basis are presented. The first type of modules have a maximum power point voltage of up to 1000 V, specific power of up to 0.245 ± 0.01 W/cm2, and efficiency of up to 25.3% under a concentration ratio range of 10–100 suns. The samples of the second module type (60,156.75 × 156.75 mm PV cells) have an open-circuit voltage of 439.7 V, a short-circuit current of 0.933 A, and a maximum power of 348 W. Additionally, two types of newly designed solar energy concentrators are described in this article: one-dimensional double-wing concentrator ensuring low Fresnel optical losses and multi-zone parabolotoric microconcentrator with the uniform radiation distribution in the focal region, as well as modules based on these concentrators and the developed PV cells. For PV modules, the maximum power degradation is 0.2–0.24% per year in a wet ammonia environment. For concentrating PV modules, this degradation is 0.22–0.37% per year. This article sets out the principles of increasing the efficiency of PV systems by increasing the level of systematization and expanding the boundaries of PV systems. The thus-created PV systems satisfy 30–50% more consumer needs. Thanks to a higher output voltage and other specific features of the developed modules, PV system loss decreased by 12–15%, and maintenance losses also decreased.

Hybrid Moth-Flame Optimization Algorithm and Incremental Conductance for Tracking Maximum Power of Solar PV/Thermoelectric System under Different Conditions

For an efficient energy harvesting by the PV/thermoelectric system, the maximum power point tracking (MPPT) principle is targeted, aiming to operate the system close to peak power point. Under a uniform distribution of the solar irradiance, there is only one maximum power point (MPP), which easily can be efficiently determined by any traditional MPPT method, such as the incremental conductance (INC). A different situation will occur for the non-uniform distribution of solar irradiance, where more than one MPP will exist on the power versus voltage plot of the PV/thermoelectric system. The determination of the global MPP cannot be achieved by conventional methods. To deal with this issue the application of soft computing techniques based on optimization algorithms is used. However, MPPT based on optimization algorithms is very tedious and time consuming, especially under normal conditions. To solve this dilemma, this research examines a hybrid MPPT method, consisting of an incremental conductance (INC) approach and a moth-flame optimizer (MFO), referred to as (INC-MFO) procedure, to reach high adaptability at different environmental conditions. In this way, the combination of the two different algorithms facilitates the utilization of the advantages of the two methods, thereby resulting in a faster speed tracking with uniform radiation distribution and a high accuracy in the case of a non-uniform distribution. It is very important to mention that the INC method is used to track the maximum power point under normal conditions, whereas the MFO optimizer is most relevant for the global search under partial shading. The obtained results revealed that the proposed strategy performed best in both of the dynamic and the steady-state conditions at uniform and non-uniform radiation.

8036 Role of endoarterial regional polychemotherapy in multimodality therapy of invasive cervix uteri cancer

Our preliminary experience with cobalt60 teletherapy in the management of patients with primary carcinoma of the cervix uteri has been based upon theories of optimal dosage obtained from previous studies. We have found that we were able to reproduce the desired levels of dosage in the parametrium by the techniques employed. The early results of treatment indicate that the basic theories seem to hold for the treatment of patients with less advanced lesions. The upper limits of what we considered optimal dose levels may not be so important in the management of patients with far-advanced lesions. The lack of severe complications of treatment at the dosage levels employed indicates that doses may well be increased with safety.Comparative studies of results in patients treated with the cobalt60 unit and those treated with the 450 kv. x-ray apparatus show a slight superiority for those in the cobalt60 series. This superiority seems to be related to a more uniform distribution of radiation throughout the parametrium. Modifications in treatment plan based upon these findings are suggested. These include only moderate increase in parametrial dose by means of external radiation for the early cases, and an appreciable increase in parametrial dose by means of external radiation with moderate limitation of the intracavitary dose from the intracavitary radiation for the advanced cases.

Airborne total eclipse observation of the extreme solar limb at 400 ?m

The total solar eclipse of February 26, 1979 was monitored at far infrared wavelengths from the NASA Lear Jet Observatory flying at 12.9 km in the eclipse shadow. The resultant eclipse curve for radiation within a bandwidth of 20 cm−1 centered upon 25 cm−1 (400 μm) was measured and analysed at an equivalent angular resolution of 1 arc sec over a 100 arc sec region adjacent to the limb to provide information on the intensity distribution of continuum radiation close to this limb. The curve has been compared to predictions derived from models of the solar atmosphere for the specific geometry of this eclipse, and is shown to match most closely that derived from a uniform distribution of radiation across the disk. This is in distinct contrast to the result obtained in the only other comparable experiment, carried out over Africa in 1973 from a supersonic Concorde aircraft, in which an intense but narrow ‘spike’ of far infrared radiation at the extreme solar limb was inferred from the data. The absence also in the present observations of the significant limb brightening predicted by the HSRA model (in which homogeneity within the source region is assumed) is in substantial agreement with lower resolution results from mountain altitudes. This result is interpreted as further evidence for the presence in the Sun's lower chromosphere of significant inhomogeneity with a scale size of at least 1000 km at this depth.

Experimental studies of relative biological effectiveness of 910-Mev alpha particles in mammalian cells.

The application of energetic heavy particles, such as neutrons, protons, and alpha particles for treatment of neoplastic and neurologic diseases is of recent development. These particles, as compared to electrons, are in fact very heavy, and they possess unique advantages over x-rays in depth of penetration and lack of scattering in tissues. As an example, 340-Mev protons and 910-Mev alpha particles from the Berkeley 184-inch cyclotron can be made to travel in a pencil-like beam which gives an almost uniform distribution of radiation along its path and can be made to result in destruction in a predetermined, small, deep-lying structure. Furthermore, these mono-energetic heavy particles have a uniform and well defined range of penetration, producing maximum ionization just before stopping in tissues, producing the so-called Bragg effect. The range of the 910-Mev alpha particles in tissue is about 22 gm./cm.2 The present report will describe a preliminary experimental investigation of the RBE of 910-Mev alpha particles from the Berkeley cyclotron, based on mouse ascites tumors. For this purpose, TA3 transplantable ascites tumor,3 which grows progressively in and finally kills A/HeJ and A/J inbred mice, was chosen. The tumor from a freshly killed animal was diluted with normal saline to a known concentration of cells, and the resulting suspension was placed in a test tube for irradiation. For Bragg peak studies, special plastic chambers 1 mm. in depth were used. After irradiation, the tumor suspension was recovered from the test tubes and the plastic chambers, counted, and transplanted into a group of 5 to 10 A/HeJ mice. Each intraperitoneal inoculum consisted of 500,000 irradiated tumor cells and 50 per cent tumor takes was used as the end point. The mice were fed with Simonson Laboratory white diet and water ad libitum and were observed for six weeks after tumor transplantation. Radiation and Dosimetry The roentgen radiation was from a Philips unit, with the following technical factors: 200 kv, 15 ma, added filtration 0.25 mm. Cu and 1 mm. Al, h.v.l. 1 mm. Cu. For the alpha particle irradiation the 910-Mev beam was deflected from the cyclotron, magnetically sorted, and collimated by the quadruple focusing method. Following its emergence from the vacuum collimating system into air, it consisted of nearly parallel streams of particles in a homogeneous beam nearly 2 inches in diameter. The dose rates ranged from 50 to 100 rads per minute for roentgen irradiation and 500 to 1,000 rads per minute for alpha irradiation. For oxygenated and anoxic experiments pure oxygen and nitrogen, respectively, were bubbled through the tumor suspension for approximately fifteen minutes before and continuously during the irradiation. Results The experimental data have been briefly summarized in Figure 1.

Early experiences in the treatment of carcinoma of the uterine cervix with cobalt60 teletherapy and intracavitary radium

Our preliminary experience with cobalt60 teletherapy in the management of patients with primary carcinoma of the cervix uteri has been based upon theories of optimal dosage obtained from previous studies. We have found that we were able to reproduce the desired levels of dosage in the parametrium by the techniques employed. The early results of treatment indicate that the basic theories seem to hold for the treatment of patients with less advanced lesions. The upper limits of what we considered optimal dose levels may not be so important in the management of patients with far-advanced lesions. The lack of severe complications of treatment at the dosage levels employed indicates that doses may well be increased with safety.Comparative studies of results in patients treated with the cobalt60 unit and those treated with the 450 kv. x-ray apparatus show a slight superiority for those in the cobalt60 series. This superiority seems to be related to a more uniform distribution of radiation throughout the parametrium. Modifications in treatment plan based upon these findings are suggested. These include only moderate increase in parametrial dose by means of external radiation for the early cases, and an appreciable increase in parametrial dose by means of external radiation with moderate limitation of the intracavitary dose from the intracavitary radiation for the advanced cases.

Uniform contact roentgen therapy for large areas; a simple device and method.

Contact roentgen therapy has certain inherent advantages due to the very short tissue-target distance and the relative low voltage employed. For the Philips contact tube these factors are 18 mm. distance and approximately 50 kv.p. This gives a source of intense irradiation of the order of 6,000 to 10,000 r per minute. The short tissue-target distance results in a very rapid falling off of intensity. The depth dose at 5 mm. is approximately 50 per cent of that at the surface, at 10 mm. 23 per cent, and at 40 mm. 1 per cent. The major disadvantage is that the tube aperture is only 2.5 cm. in diameter. Many thin lesions, both benign and malignant, such as hemangiomas, calluses, keloids, and some epitheliomas, for which the short tissue-target distance and low voltage would be advantageous, are too large for so limited a treatment field. Large-field contact therapy may also be desirable in cases in which the bulk of a tumor has been removed surgically, for intensive irradiation of the tumor base. Two methods have been used in the contact treatment of large areas. One consists in moving the tube, while energizing it, over the area to be treated; in the other the tube is moved from spot to spot, in an attempt to cover the entire lesion. With these methods it is difficult, if not impossible, to get a uniform distribution of radiation (1–3). In order to obtain uniform irradiation of a surface or plane, one of us (E. F. L.) has designed a grid containing squares measuring 1.5 × 1.5 cm. These are the largest squares which can be included within the 2.5 cm. round field of the tube. The grid consists of a sheet of lead, 22 × 22 cm., approximately 0.5 mm. thick, having an aperture in the center measuring 18 cm. on a side. A net is fashioned from nylon fishing line, having meshes 1.5 cm. square, the line being anchored to the lead by staples and stitches. Where the nylon lines cross, they are attached by passing a thread through the line and tying. This is done to avoid any distortion of the field, which is particularly important in treating uneven surfaces. This grid may be sterilized in any manner and used repeatedly. It furnishes uniform radiation to the surface and will fulfill most practical needs. For thicker lesions, in which it is desired to obtain uniform irradiation of other planes than the surface, the 1.5-cm. squares of the grid may be spaced at varying distances, depending upon the depth at which the uniform radiation is desired. For instance, for a plane 5 mm. below the surface, a spacing of 4 mm. is required. The radiation is not uniform below the plane of uniform irradiation because of the geometric spread resulting from the short target-tissue distance and subsequent overlap. The volume of tissue involved in this overlapping is, however, minimal (Fig. 1). Lead rubber can also be used for making the grid.

Intravaginal Roentgen Irradiation of Cancer of the Cervix

This paper presents another method for the intravaginal roentgen irradiation of cancer of the cervix. Technic Cylinders, as shown in Figure 1, are used to limit the distribution of the rays. These cylinders are made of brass with the thickness of the wall suitable to the voltage used. The diameter of the cylinders varies from 2 to 4 cm., and the size selected for the individual case is that necessary to fit the vaginal orifice just snugly. A light such as used in the proctoscope (Fig. 2) is fitted to the various cylinders by ring adjusters of appropriate size. These rings and the proctoscopic light, with inflation as used in the ordinary proctoscope, enable the operator to inflate the vagina and to place the cylinder in the desired position in relation to the cervix. This apparatus, consisting of a cylinder and proctoscopic light, with air inflation (Fig. 3), will be found to be of unusual value in the examination of the vagina and to have a distinct advantage over the customary “bivalve speculum.” With the cylinder in the vagina and in proper position, and the rays directed into any desired plane of the pelvis, the light and inflation bulb are removed. The apparatus containing the x-ray tube (Fig. 4) may then be brought into contact with the cylinder and clamped in position. Clamps suitable for holding the cylinder either to the table or to the apparatus containing the x-ray tube may be easily designed for any make of equipment. The table should be clamped in position on the floor and likewise the x-ray tube should be held firmly in position. A periscope (Fig. 4) is desirable for checking the position of the cylinder after the apparatus and table have been clamped in position. This entire procedure will take very little longer than the time required for the insertion of the ordinary vaginal speculum and with no discomfort to the patient. Any desired kilovoltage may be used and any length of time of exposure. I have found, after three years' experience with this technic, that 200 kv., with the usual factors, is the preferred voltage; 140 kv.-technic may be used in some very superficial conditions. Intravaginal irradiation is always combined with external roentgen irradiation of the pelvis; 250 to 300 r as measured in air are administered to each area at each treatment, and one to two areas are treated daily. The number of areas treated and the dosage to each area are dependent upon the external radiation that has been or is being given. The cylinders may be angled to direct the rays into the cervix or into the broad ligaments or any portion of the pelvis. An excellent plan which gives a uniform distribution of radiation throughout the pelvis is that shown in Figure 5. Here the first treatment, 1, is given directly into the cervix. Areas 2, 3, 4, and 5, are then treated clockwise as shown in the figure with the cylinder angled to the proper degree to cover the entire pelvis. The intravaginal end of the cylinder should be far enough from the cervix to include the vaginal wall some distance from the visible lesion in order to include in the area of irradiation all possible malignant tissue.