Sparsity-Inducing Fuzzy Subspace Clustering

This paper considers a fuzzy subspace clustering problem and proposes to introduce an original sparsity-inducing regularization term. The minimization of this term, which involves a l$_{0}$ penalty, is considered from a geometric point of view and a novel proximal operator is derived. A subspace clustering algorithm, Prosecco, is proposed to optimize the cost function using both proximal and alternate gradient descent. Experiments comparing this algorithm to the state of the art in sparse fuzzy subspace clustering show the relevance of the proposed approach

A combination of capillary and dielectrophoresis-driven assembly methods for wafer scale integration of carbon-nanotube-based nanocarpets

The wafer scale integration of carbon nanotubes (CNT) remains a challenge for electronic and electromechanical applications. We propose a novel CNT integration process relying on the combination of controlled capillary assembly and buried electrode dielectrophoresis (DEP). This process enables us to monitor the precise spatial localization of a high density of CNTs and their alignment in a pre-defined direction. Large arrays of independent and low resistivity (4.4 x 10-5 omega m) interconnections were achieved using this hybrid assembly with double-walled carbon nanotubes (DWNT). Finally, arrays of suspended individual CNT carpets are realized and we demonstrate their potential use as functional devices by monitoring their resonance frequencies (ranging between 1.7 and 10.5 MHz) using a Fabry–Perot interferometer

Parallel Copy Motion

International audienceRecent results on the static single assignment (SSA) form open promising directions for the design of new register allocation heuristics for just-in-time (JIT) compilation. In particular, heuris- tics based on tree scans with two decoupled phases, one for spilling, one for splitting/coloring/coalescing, seem good candidates for de- signing memory-friendly, fast, and competitive register allocators. Another class of register allocators, well-suited for JIT compilation, are those based on linear scans. Most of them perform coalesc- ing poorly but also do live-range splitting (mostly on control-flow edges) to avoid spilling. This leads to a large amount of register-to- register copies inside basic blocks but also, implicitly, on critical edges, i.e., edges that flow from a block with several successors to a block with several predecessors. This paper presents a new back-end optimization that we call parallel copy motion. The technique is to move copy instructions in a register-allocated code from a program point, possibly an edge, to another. In contrast with a classical scheduler that must preserve data dependences, our copy motion also permutes register assign- ments so that a copy can "traverse" all instructions of a basic block, except those with conflicting register constraints. Thus, parallel copies can be placed either where the scheduling has some empty slots (for multiple-issues architectures), or where fewer copies are necessary because some variables are dead at this point. Moreover, to the cost of some code compensations (namely, the reverse of the copy), a copy can also be moved out from a critical edge. This pro- vides a simple solution to avoid critical-edge splitting, especially useful when the compiler cannot split it, as it is the case for abnor- mal edges. This compensation technique also enables the schedul- ing/motion of the copy in the successor or predecessor basic block. Experiments with the SPECint benchmarks suite and our own benchmark suite show that we can now apply broadly an SSA-based register allocator: all procedures, even with abnormal edges, can be treated. Simple strategies for moving copies from edges and locally inside basic block show significant average improvements (4% for SPECint and 3% for our suite), with no degradation. It let us believe that the approach is promising, and not only for improving coalescing in fast register allocators

Industrial Services Characterization for Bidding Process

International audienceWhen responding to call for tenders, many bidding companies offer services. This paper focuses on how to model industrial services during the bidding process to be able to easily develop them. A product offer configuration model is presented, then a reflection about the extension of this model to service offers is conducted. A study of the literature about service definition is dealt and services characteristics are identified. Their impact on the product offer model is analyzed and new characteristics are introduced. This work makes possible to propose a typology to adapt the product offer model to services

Revisiting Out-of-SSA Translation for Correctness, Code Quality, and Efficiency

Compared to the previous versions, the only change is correcting an awful typo that made Algorithm 1 wrong. Line 18 is not "if b = loc(pred(b))" but simply "if b = loc(b)".Static single assignment (SSA) form is an intermediate program representation in which many code optimizations can be performed with fast and easy-to-implement algorithms. However, some of these optimizations create situations where the SSA variables arising from the same original variable now have overlapping live ranges. This complicates the translation out of SSA code into standard code. There are three issues to consider: correctness, code quality (elimination of copies), and algorithm efficiency (speed and memory footprint). Briggs et al. proposed patches to correct the initial approach of Cytron et al. A cleaner and more general approach was proposed by Sreedhar et al., along with techniques to reduce the number of generated copies. We propose a new approach based on coalescing and a precise view of interferences, in which correctness and optimizations are separated. Our approach is provably correct and simpler to implement, with no patches or particular cases as in previous solutions, while reducing the number of generated copies. Also, experiments with SPEC CINT2000 show that it is 2x faster and 10x less memory-consuming than the Method~III of Sreedhar et al., which makes it suitable for just-in-time compilation

Product v Service system configuration: a generic knowledge-based model for commercial offers

At a time when modes of consumption are rapidly evolving, consumer attitudes and expectations are changing. Today, customers want more and more products and services that can be customised to their needs. Furthermore, they are more willing to pay for usage of a product rather than ownership. On the other hand, companies are adding more and more services to the products they are bringing to market in order to create added value and differentiate themselves from their competitors. To adapt to these new market trends, companies now have to offer their customers a more sophisticated catalog of solutions, in both product and services, including all conceivable combinations of the two. The aim of this article is to propose a generic knowledge-based model, dedicated to commercial offer configuration which is able to cope with the whole variety of solutions a company can deliver. To our knowledge, although some works on product configuration, service and product-service system configuration exist, none of them is generic enough to support product, service and product-service configuration at the same time when defining commercial offers. In this article, after giving a state-of-the-art assessment of product and service configurations, the need for a generic model able to cover the whole range and diversity of commercial offers is established, a knowledge-based model is defined and its relevance is demonstrated on seven use-cases coming from secondary and tertiary sector companies

From micro-OPs to abstract resources: constructing a simpler CPU performance model through microbenchmarking

This paper describes PALMED, a tool that automatically builds a resource mapping, a performance model for pipelined, super-scalar, out-of-order CPU architectures. Resource mappings describe the execution of a program by assigning instructions in the program to abstract resources. They can be used to predict the throughput of basic blocks or as a machine model for the backend of an optimizing compiler. PALMED does not require hardware performance counters, and relies solely on runtime measurements to construct resource mappings. This allows it to model not only execution port usage, but also other limiting resources, such as the frontend or the reorder buffer. Also, thanks to a dual representation of resource mappings, our algorithm for constructing mappings scales to large instruction sets, like that of x86. We evaluate the algorithmic contribution of the paper in two ways. First by showing that our approach can reverse engineering an accurate resource mapping from an idealistic performance model produced by an existing port-mapping. We also evaluate the pertinence of our dual representation, as opposed to the standard port-mapping, for throughput modeling by extracting a representative set of basic-blocks from the compiled binaries of the Spec CPU 2017 benchmarks and comparing the throughput predicted by existing machine models to that produced by PALMED

Configuration and Response to calls for tenders: an open bid configuration model

During bidding process, bidders have to submit offers which will suit the customers' requirements. The OPERA project aims at building a decision support tool to help bidders to design offers using CSP and compare them on orignial indicators. The objective is (1) to help bidder to have the same routine for bid answer-ings (2) to help them to design more accurate responses and more efficiently. One of the major tasks during bidding process is offer elaboration, which is in our case, 90% a configuration problem and 10% an innovative design one. Four industrial partners are part of the OPERA project: two in the secondary sector and the two others in tertiary one. This paper presents the first results of this project for open bidding configuration. Therefore, we have built a first version of an open generic bidding model which gathers three types of offers data: (1) context characterization data, (2) data defining the product or service and (3) data defining its delivery process, in case of success. Context data allow to characterize the customer profile, the call for tender characteristics, the bidder profile and the environmental factors. The product is decomposed on subsystems and components using a bill of materials and we propose some tracks to extend our model to services. The process is composed of activities, characterized by a couple (resources, workload). This model has been tested on one use case for each industrial partner. This paper is illustrated by a generic instance of a bike open bidding configuration