Gen X: ExCALIBUR working group on Exascale continuum mechanics through code generation.

连续的物理过程渗透到我们社会、工业和自然世界的各个方面。从飞机上的空气流动到移动的电话信号的传播，再到制造过程中每一点的化学成分行为，连续介质力学是我们工业过程的核心。在医学上，心脏和大脑的电行为，血液和其他液体在体内的流动，以及使用各种扫描仪和探测器检测疾病都是连续的机械过程。在自然世界中，检测和了解地球的运动和组成使我们能够了解地震并寻找有价值的矿物，而对流体和电磁场复杂相互作用的深入了解使我们能够了解恒星、宇宙以及我们在其中的位置。在所有这些情况下以及除此之外的许多情况下，描述现象的数学方程是已知的，但解决方案却很少存在。科学和工程基本上依赖于计算机模拟来理解这些系统，并设计使用它们的设备和过程。许多这些现象是如此复杂或有这样一个范围的空间尺度，现有的千万亿次计算机系统是对科学进步的限制。此外，需要超越单纯的模拟来模拟过程中的不确定性，找到最佳解决方案，或发现系统的多种可能结果。艾级计算的出现为解决这些限制提供了机会。然而，不断增加的计算规模、日益复杂的模拟算法以及由亿亿级计算产生的大量数据将不仅击败现有的模拟软件，而且击败现有的编写模拟软件的方法。Gen X是一个建立连续介质力学的亿级模拟软件要求的项目，并提供在未来五年内实现这一能力的具体方法。X世代的方法是超越仅仅编写代码到一个专家模拟语言系统，使科学家和工程师能够通过编写数学，科学语言来指定他们想要解决的问题和算法。实际的代码将由专业编译器自动生成，而不是手工编写。而不是一个算法开发人员写一篇关于他们的新发展的论文，并希望仿真科学家将找到时间来编码它为他们的特定问题，算法将被编码在一个特定领域的语言和实现在其编译器。这样，仿真科学家就可以直接访问算法而无需重新编码。在兆级，将所有的仿真输出写入磁盘供以后分析是不可能的。相反，模拟数据必须在模拟进行时进行处理，分析和可视化，并且只存储结果以供以后使用。第X代将为这一过程提供专业语言，使科学家或工程师能够简明地指定要执行的分析，并确信所产生的计算将是有效和正确的。通过使科学家和工程师能够在更高的专业水平上工作，同时也能获得比以前更复杂的算法和硬件特定的实现，X世代将使模拟科学更有能力，更有成效。通过这种方式，X世代对于实现百亿亿次计算的潜力，同时最有效地利用研究资源至关重要。

Continuous physical processes pervade every aspect of our society,industry and the natural world. From the flow of air over an aircraftto the propagation of mobile phone signals, to the behaviour ofchemical components at every point of the manufacturing processes,continuum mechanics is at the heart of our industrial processes. Inmedicine, the electrical behaviour of the heart and brain, the flow ofblood and other fluids through the body, and the detection of disordersusing all manner of scanners and detectors are all continuum mechanicsprocesses. In the natural world, detecting and understanding themovement and composition of the Earth enable us to understandearthquakes and to hunt for valuable minerals, while advancedunderstanding of the complex interaction of fluids and electromagneticfields allows us to understand stars, the cosmos and our place in it.In all of these cases and many more beside, the mathematical equationsdescribing phenomena are known, but solutions very rarelyexist. Science and engineering are essentially dependent on computersimulation to understand any of these systems, and to design thedevices and processes which use them. Many of these phenomena are socomplex or have such a range of spatial scales that existing petascalecomputer systems are a limit on scientific advance. In addition, thereis a need to go beyond mere simulation to simulate the uncertainty inprocesses, find the optimal solution, or discover the multiplepossible outcomes of a system. The advent of exascale computingpresents the opportunity to address these limitations. However,increasing computational scale, increasingly complex simulationalgorithms, and the vast quantities of data produced by exascalecomputing will defeat not just existing simulation software, but alsoexisting ways of writing simulation software.Gen X is a project to establish the requirements for exascalesimulation software for continuum mechanics, and to provide a concreteway of achieving this capability within the next five years. The Gen Xapproach is to move beyond just writing code to a system of specialistsimulation languages which enable scientists and engineers to specifythe problem they want to solve and the algorithms they want by writingmathematics, the language of science. The actual code will beautomatically generated by specialist compilers rather thanhand-written. Rather than an algorithm developer writing a paper abouttheir new development and hoping that simulation scientists will findthe time to code it up for their specific problem, the algorithm willbe encoded in a domain specific language and implemented in itscompiler. The simulation scientist will then be able to access thealgorithm directly without recoding.At exascale, writing all the simulation outputs to disk for lateranalysis is impossible. Instead, simulation data must be processed,analysed and visualised as the simulation is conducted, and only theresults stored for later use. Gen X will provide mathematicallanguages for this process which will enable the scientist or engineerto concisely specify the analysis to be performed, and to haveconfidence that the resulting calculations will be both efficient andcorrect.By enabling scientists and engineers to work at a higher mathematicallevel while also accessing more sophisticated algorithms andhardware-specific implementations than previously possible, Gen X willmake simulation science both more capable and more productive. In thismanner, Gen X is essential to realising the potential of exascalecomputing while also making the most efficient use of researchresources.