Transmittance computation is the most time consuming part of the radiative transfer model. One way to implement it on a GPU is to divide the workload so that each thread computes results for a level. Each CUDA thread would in effect be computing a matrix by vector multiplication between coefficients and predictors. In BLAS terms, it is a batched SGEMV operation. Since there are only 101 levels there would be only 101 threads. Compared to the more than 30,000 active threads available on Tesla C1070 this is extremely low number for a CUDA threading model. NVIDIA recommends that the number of threads per block should be a multiple of 32 threads [30]. Thus, 101 threads could effectively use at most 4 out of the 30 multiprocessors. Since this type of work division is not very efficient we will next describe in detail implementations that divide the work so that each thread computes results for a channel. 3.6 GPU implementation using 6 CUDA kernels We are implementing radiance computation on a GPU using six kernels, five for transmittance computation and one for radiance computation. Our GPU implementation of the transmittance of radiative transfer model in illustrated in Figure 6. It demonstrates what happens inside each of the 30 multiprocessor inside a Tesla C1070 during layer-to-space transmittance computation. Also, shared memory utilization for storing predictors for the effective layer optical depths is illustrated. The most time consuming part of the radiative transfer model are the dot products in a layer-to-space transmittance computation as shown in Fig. 3. The dot product between regression coefficients for predicting the effective layer optical depths, 'C', and predictors for the effective layer optical depths, 'X',... ... middle of paper ... ...xecution, pre-computed values, Sqp, are stored in the shared memory. Sqp represents the square root of a slant-path gas layer amount. For each level, 101 threads take part in transferring values of predictors for the effective layer optical depths of the fixed gases, variable X, to the shared memory and the threads are synchronized. After that, a dot product between coefficients and values of variable X is computed. This operation is the most time consuming one in the kernel due to a large amount of global memory accesses. The global memory access pattern for the coefficients using in the dot product is such that consecutive threads access consecutive memory addresses. This maximizes the memory bandwidth utilization. Similar kernels are used for the other transmittance components and for brevity’s sake we do not present the other transmittance kernels in this paper.
Absorbance was defined as: log I_o/I where I_o is incident light and I is the transmitted light. Fluorescence emission spectrum is different from fluorescence excitation spectrum because it records different wavelengths of chemical s...
Companies that render high quality images for posters or produce high quality images for movies and web design may use multiprocessing enabled machines because they can render these images and support these programs with a dramatic decrease in latency issues. If the same programs or images were to be rendered on a standard home computer it could take years or the program could altogether crash as the PC doesn’t have the processing power to support the program.
The rate (V0) was calculated by plotting the absorbance against time, where the slope of the line indicates
Spectrophotometry is a widely used method to calculate how much light is absorbed by a chemical substance. This is done by measuring the intensity of light as it passes through a sample solution. The principle of this method is that a compound absorbs or transmits light over a certain wavelength from which the measurement can be used to calculate the concentration of a known chemical substance.
Gallik, Stephen. "Spectrophotometry: Transmittance and Absorbance." Cell Biology OLM. N.p., n.d. Web. 26 Jan. 2014. .
capture the full effect of light during this short period of the day with the study
Weng, Y., Kuo, K.N., Yang, C., Lo, H., Chen, C., & Ya-Wen, C. (2013). Implementation
Meteorologists are able to calculate the UV value using a variety of tools. Using satellites, they
simultaneous multithreading allows instructions to be reordered acrossthreads; that is, rather than having the operating system perform con-text switches between two threads, it can schedule both threads simul-taneously on the same processor, and instructions will be interleaved,dramatically increasing the utilization of existing execution resources.On the 2.8 GHz Intel Pentium 4 with Hyper-Threading processor,with which the remainder of this paper is concerned2, the two threadsbeing executed on each processor share more than merely the execu-tion units; of particular concern to us, they share access to the memorycaches [8]. Caches have already been demonstrated to be cryptograph-ically dangerous: Many implementations of AES [9] are subject to tim-ing attacks arising from the non-constancy of S-box lookup timings [1].
Parallel Computing, in its basic sense, is multiple operations being carried out simultaneously, that is, a problem can be divided into sub problems which can be solved concurrently. Throughout the history, attempts have been made and have been successful to increase the degree of parallelism in computing as much as possible. During this course, many restrictions have been encountered and alongside the possible solutions were suggested by the brightest minds. Parallelism can be divided in many ways:
Kennedy, Gerry. "The Spectronics Blog." The Spectronics Blog RSS. Spectronicsinoz, 15 May 2012. Web. 04 Mar. 2014.
Many physical and engineering problems cannot be solved without the help of complex computer simulations. These require intensive mathematical work, and so take advantage of a mainframe's computational power. Examples include weather forecasting, or calculating the position of astronomical bodies with extreme accuracy. Many minicomputers or workstations are now used for this type of problem.
These radiates are electromagnetic one. it may also be named as the total power in respect with the wavelength visible to the eye. The amount of this light has different wavelengths that changes in respect to the human eye when confronted and Lumens is the measuring parameter unit. The total amount of these flux is then has to be integrated over all the wavelength to get the luminous flux afterwards as mentioned by William in 2011.
effect. A lot of the rays from the sun are absorbed by water vapor that is naturally in our
For instance, the future of the RAM technology is headed in the development of the “Holographic Memory”. The implications of this type of memory are that it will provide a significant amount of data to be easily stored on tiny chips. However, it is important to note that the major limitation that will be associated with such a kind of memory is the size of both reading and writing of the optical systems. Quite obviously and definitely, this kind of future memory is not genuinely ready for Personal Computer (PC)