SEND Operations

A modified version of the C function in Figure 3.1 using an MPI non-blocking receive, MPI Irecv, to avoid deadlock. The MPI Irecv returns without waiting for any message to arrive, and each process then proceeds to post the sending operation, MPI Send. The MPI Wai t causes each process to wait at this point until the message to be received by MPI Irecv has arrived. The employed MPI functions are explained in Appendix A. 

The send operations employed are non-blocking and can be overlapped with computation to some extent. Our performance model will take this into account by using effective a and /3 values measured for overlapped communication and computation. From Eq. 9.12 it is clear that the overall communication requirement for the P2 algorithm, namely, the total amoimt of data that must be sent per process, O( sheii0 n / p), is roughly inversely proportional to the number of processes, which is a prerequisite for a strongly... 

Management must be particularly cautious when sending operators and maintenance workers into a hazardous situation in order to correct problems. It is likely that additional safeguards and precautions will be needed. 

An example of Process Creation is shown in Figures 3-16 and 3-17. In this example, before the transformation, vtbody VI A CALLs vtbody V2 B, passing it values x and y. After the transformation, the CALL has been replaced with a SEND operator, and a corresponding RECV operator has been added to the beginning of vtbody V2 B values x and y are now passed via these message-passing operators. The LEAVE operator is replaced by a similar pair of SEND / RECV operators. After the transformation, vtbody V2 B is marked as a process, and is RESTARTed to execute continuously. 

Monitoring and control of the production process will be performed by a combination of instrumentation and control equipment plus manual involvement. The level of sophistication of the systems can vary considerably. For example, monitoring well performance can be done in a simple fashion by sending a man to write down and report the tubing head pressures of producing wells on a daily basis, or at the other extreme by using computer assisted operations (CAO) which uses a remote computer-based system to control production on a well by well basis with no physical presence at the wellhead. 

A hands-on experience with the method is possible via the SPINUS web service [48. This service uses a client-server model. The user can draw a molecular structure within the web browser workspace (the client), and send it to a server where the predictions are computed by neural networks. The results are then sent back to the user in a few seconds and visualised with the same web browser. Several operations and different types of technology arc involved in the system ... 

To ensure proper sensing of the incoming current and its phase displacement by the relay it i.s es.senlial that the CTs ratio and their VA burden chosen for the required duty are close to the actual requirement as noted in Table I. S.8.. Sometimes this fact is overlooked and CTs with a much higher VA burden or ratio or both are chosen while the secondary circuit may not be adequately loaded. In this case the CTs may not accurately transform the primary parameters to the secondary and. in turn, the relay may not send accurate signals. Moreover, the relay itself may operate only at minimum 19c or more of its rated current (I or 5 A), depending upon its design and type (lEC 60051-1). 

A coking operation has about 1 million cubic meters per year of excess coke oven gas that it generally sends to flares. (A) Instead of burning this offgas in flares, what else could be done with it (B) What is the value of this gas (assume it to be essentially natural gas or methane) ... 

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