Approach for Predicting Production Scenarios Focused on Cross Impact Analysis

AbstractOne of the most consistent challenges in business is anticipating what the future holds and what impact it may have on current production systems. The scenario technique is a well-established method for developing and forecasting multiple future development paths for companies. However, this method is mostly employed to develop and to support strategic long-term decisions. The core idea of the approach introduced in this paper is to convey the future impact of today's decisions on production systems to employees involved in production planning processes. With the help of immersive visualization, performed in virtual reality (VR) systems, planning participants can perceive how the factory must adapt to fit future demands.In this paper, the focus is on the fourth phase of the scenario technique – so called scenario development – and, in particular, the cross impact analysis. With this methodology, the interrelations, or cross impacts of the different basic elements are determined. The cross impact analysis results serve as a basis for the development of a standardized tool that can be used to create probable production scenarios out of given production systems. This standardized tool will facilitate the usage of the scenario technique for factory planning projects, as it focuses the immense diversity of future uncertainties companies are faced with on the factory level

CP2K: An electronic structure and molecular dynamics software package - Quickstep: Efficient and accurate electronic structure calculations

CP2K is an open source electronic structure and molecular dynamics software package to perform atomistic simulations of solid-state, liquid, molecular, and biological systems. It is especially aimed at massively parallel and linear-scaling electronic structure methods and state-of-the-art ab initio molecular dynamics simulations. Excellent performance for electronic structure calculations is achieved using novel algorithms implemented for modern high-performance computing systems. This review revisits the main capabilities of CP2K to perform efficient and accurate electronic structure simulations. The emphasis is put on density functional theory and multiple post–Hartree–Fock methods using the Gaussian and plane wave approach and its augmented all-electron extension

Improving the Performance of sparse LU Decomposition in GEMPACK

In GEMPACK the computational general equilibrium (CGE) model is solved in its linearized form.In this form, the solution to the CGE model is computed by solving a sparse non symmetric linear system of equations(LSE). In most computer programs, the solution to a LSE is computed either by using matrix decomposition methods (direct), iterative methods or subspace methods. GEMPACK employs a sparse LU decomposition with iterative refinement to solve the LSE. Until GEMPACK 12 these solvers purely relied on algorithms from the Harwell Subroutine Library (HSL) with MA48 as the default solver. While computationally efficient, computing the LU decomposition using these off-the-shelf routines remained the time limiting step for many CGE models. In this paper, we will present a new algorithm for the analysis phase and other improvements to the original HSL routines which greatly improve the solution time for most CGE problems. The preparation stage for the analysis phase involves the reorganisation of the matrix into strong components. By replacing the original modified Hopcroft-Karp algorithm with a tree grafting algorithm to determine a suitable bipartite matching the relative time spent can be reduced by a large factor. The most time consuming part in the analysis phase is the determination of a suitable pivot structure. We developed series of buffered sorted data structures, lower bound estimates and an on-the-fly partitioning of the matrix into sparse and full processed parts which efficiently handles this problem. The new algorithm is able to find a suitable pivot structure with lower number of fill-ins at a significantly reduced cost than the original MA48 solver. For the most common CGE problems we see reductions in solution time by a factor 5 to 10

Cp2k: atomistic simulations of condensed matter systems

cp2k has become a versatile open-source tool for the simulation of complex systems on the nanometer scale. It allows for sampling and exploring potential energy surfaces that can be computed using a variety of empirical and first principles models. Excellent performance for electronic structure calculations is achieved using novel algorithms implemented for modern and massively parallel hardware. This review briefly summarizes the main capabilities and illustrates with recent applications the science cp2k has enabled in the field of atomistic simulation

Combining linear-scaling DFT with subsystem DFT in born-oppenheimer and ehrenfest molecular dynamics simulations: From molecules to a virus in solution

In this work, methods for the efficient simulation of large systems embedded in a molecular environment are presented. These methods combine linear-scaling (LS) Kohn–Sham (KS) density functional theory (DFT) with subsystem (SS) DFT. LS DFT is efficient for large subsystems, while SS DFT is linear scaling with a smaller prefactor for large sets of small molecules. The combination of SS and LS, which is an embedding approach, can result in a 10-fold speedup over a pure LS simulation for large systems in aqueous solution. In addition to a ground-state Born–Oppenheimer SS+LS implementation, a time-dependent density functional theory-based Ehrenfest molecular dynamics (EMD) using density matrix propagation is presented that allows for performing nonadiabatic dynamics. Density matrix-based EMD in the SS framework is naturally linear scaling and appears suitable to study the electronic dynamics of molecules in solution. In the LS framework, linear scaling results as long as the density matrix remains sparse during time propagation. However, we generally find a less than exponential decay of the density matrix after a sufficiently long EMD run, preventing LS EMD simulations with arbitrary accuracy. The methods are tested on various systems, including spectroscopy on dyes, the electronic structure of TiO₂ nanoparticles, electronic transport in carbon nanotubes, and the satellite tobacco mosaic virus in explicit solution

Comparison Between Endoscopic Vacuum Therapy and Conventional Treatment for Leakage After Rectal Resection

Background!#!Anastomotic leakage after rectal resection represents a severe complication for the patient and requires an early and appropriate management. Endoscopic vacuum therapy (EVT) has become the treatment of choice for anastomotic leakage after rectal resection in several institutions in Germany, and commercially available systems are currently distributed in approximately 30 countries worldwide. However, there is no evidence that EVT is superior to any other treatment for anastomotic leakage after rectal resection.!##!Methods!#!Twenty-one patients treated with EVT for anastomotic leakage after rectal resection were retrospectively compared to a historical cohort of 41 patients that received conventional treatment. Primary endpoints were death, treatment success and long-term preservation of intestinal continuity. Secondary endpoints were length of hospital stay and duration of treatment.!##!Results!#!There was no difference in mortality (p = 0.624). The intention-to-treat analysis showed a significantly higher success rate of EVT compared to conventional treatment (95.2% vs. 65.9%, p = 0.011). EVT was associated with preservation of intestinal continuity in a significant higher percentage of patients than patients undergoing conventional treatment (86.7% vs. 37.5%, p = 0.001). Conventional treatment tended to a shorter length of hospital stay (31.1 vs. 42.2 days, p = 0.066) but with no difference in overall duration of treatment. Time until closing of a diverting stoma did not differ between groups (10.2 months in the EVT group vs. 9.4 months in the conventional treatment group, p = 0.721).!##!Conclusion!#!According to this retrospective study, conventional therapy and EVT are both options for the treatment of anastomotic leakage after rectal resection. EVT might be more effective in terms of definite healing and preservation of intestinal continuity