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...
"IBM's ASCC introduction." IBM Archives: IBM's ASCC (a.k.a. The Harvard Mark I). Ed. IBM. IBM. 11 Apr. 2014 .
Contributor: Gunter Wyszecki, Dr. Eng., Former Director of the Institute of Optics, National Research Council of Canada.
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].
This is the simplest kind of architecture. This is equivalent to an entirely sequential program and hardly employs any parallelism.
When it comes to computation speed, GPU provides a huge edge over the CPU making the GPU one of the most interesting areas of research in the field of modern industrial research and development.
Multiplier is key fundamental component for many high performance systems such as FIR-filters, microprocessors, digital processors, multimedia applications etc. Multiplier plays main role in system performance [3] [4] [5] because multiplier is generally the slowest element in the system. Furthermore, it occupied a large silicon area. Hence, optimizing speed and area are major design issues however area and speed both are conflicting performance constraints’.
Radiate, by definition, means to send or spread out, and this is important to know when thinking about how exactly radiation occurs. We already discussed a child coming in from playing out in the snow, snuggling up to their father and getting warm through heat transfer by conduction- physical contact. Now, let’s say that the child comes inside from out in the cold, takes off their snow gear and places their hands over a hot fire instead. The child’s hands will warm up through the transfer of heat energy through radiation. Another example, which can be seen every day that you walk outside and the sun is shining bright- is the heat received on Earth by the sun, through the means of radiation. The Earth receives heat through the electromagnetic waves, and our bodies feel the warmth of the sun from these waves that are absorbed within our skin. Radiation is the only means by which heat energy can transfer through the empty space between Earth and the sun- neither conduction or convection have the ability to play a role in this area and therefore, we can see how truly important radiation is. Another interesting fact in regards to radiation is that “because more heat is radiated at higher temperatures, a temperature change is accompanied by a color change. For example, an electrical element on a stove glows from red to orange, while the
There are the two main approaches used in optical multiplexing. One is optical wavelength division (frequency division) other is optical time division Multiplexing. This paper deals with optical time division Multiplexing.
effect. A lot of the rays from the sun are absorbed by water vapor that is naturally in our
Ham radios are the communication tools used by a large number of people across the world to connect with their friends. Ham radios are used universally for communication purposes; however, despite being outdated, these radios have still not lost their essence. Therefore, in order to provide a manual regarding its use, this book, Ham Radio Guide: Quick Start Ham Radio Guide- from Beginner to advanced, has been written.
Because the index of refraction of air (nair), in the precision this lab delves into, is 1.00, the resulting equation is essentially:
The graph above demonstrates that as the light sensor is further away from a light source, the less bright the source is. This mea...
People in the present society have turned from the use of the old means of communication to the more advanced and technological ways of communicating. Technology has made it easier for people to communicate in a faster, efficient, and cost saving means through the introduction of the communication channels. The world has turned out to be the centre for technology with different technologies emerging daily as the people continue to develop from time to time to cope with the growing technology. The benefits of adopting the communication technology are explained in this article which shows why people do not function without technology.
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.