5,706 research outputs found
Inertia and Change in the Early Years: Employment Relations in Young, High Technology Firms
[Excerpt] This paper considers processes of organizational imprinting in a sample of 100 young, high technology companies. It examines the effects of a pair of initial conditions: the founders\u27 models of the employment relation and their business strategies. Our analyses indicate that these two features were well aligned when the firms were founded. However, the alignment has deteriorated over time, due to changes in the distribution of employment models. In particular, the \u27star\u27 model and \u27commitment\u27 model are less stable than the \u27engineering\u27 model and the \u27factory\u27 model. Despite their instability, these two blueprints for the employment relation have strong effects in shaping the early evolution of these firms. In particular, firms that embark with these models have significantly higher rates of replacing the founder chief executive with a non-founder as well as higher rates of completing an initial public stock offering. Some implications of these findings for future studies of imprinting and inertia in organizations are discussed
A PATH ENUMERATION REFORMULATION OF THE SCHEDULE MIXED INTEGER PROGRAM SUPPORTING EXPEDITIONARY ADVANCED BASE OPERATIONS.
The U.S. Marine Corps needs an accurate model for analyzing its logistical needs in support of Expeditionary Advanced Base Operations (EABO). EABO is a doctrinal method used by the U.S. Navy and Marine Corps for denying adversary forces access to the maritime global commons. Deployment and sustainment of forces engaged in EABO requires a distribution network supported by various surface and airborne connector platforms of differing capacity and speed. The Marine Corps currently has a model for analyzing its distribution networks in support of EABO, the Schedule Mixed Integer Program (S-MIP). However, the computational difficulty of S-MIP limits its usefulness in large-scale experiments. This thesis describes a path enumeration-based reformulation known as the Path Enumeration Mixed-Integer Program (PE-MIP). PE-MIP is designed to provide a less computationally difficult model than the antecedent model S-MIP. We compare the runtime of PE-MIP and the quality of its solutions with that of S-MIP model and find that PE-MIP provides faster and superior results to S-MIP. The application of PE-MIP by the research sponsor will further inform current Marine Corps and Navy operational plans, acquisition, and force structure decisions.Operational Analysis Directorate, USMC, QUANTICO, VA, 22134Major, United States Marine CorpsApproved for public release. Distribution is unlimited
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A preliminary philosophy for ARCTURUS : an advanced highly-integrated programming environment
At Irvine, we are currently in the initial stages of designing a programming environment, called Arcturus. This paper is a report of work in progress giving our preliminary philosophy and expressing preliminary thoughts on an initial Arcturus design.Arcturus is an advanced, highly-integrated programming environment intended for use in the late 1980s. We assume that programmers will each be equipped with large flat-screen displays driven by powerful desk-top computers linked into local networks by high band-width channels, and that shared central resources such as archival databases and multifont printing systems will be available.Arcturus is aimed at "programming in the large", that is, programming by many people, on large programs, with maintenance lifetimes of many years. In such a user setting, problems of management, documentation, training, testing, version control, diagnosis, and debugging must be solved effectively by people who, for the most part, are not authors or designers of the original system.Some preliminary design concepts that Arcturus supports are as follows:(1) Arcturus supports a "rapid prototyping" language -- a very high level, strongly extensible language useful for rapid construction of working prototypes of systems (emphasizing cheap, rapid construction at the expense of running efficiency and polish).(2) Arcturus supports refinement of these prototype programs, or protoprograms, for short, into programs written in program design languages (or PDLs) , which express designs. PDL programs are ultimately refined into concrete, detailed, optimized programs expressed in an implementation language.(3) Arcturus supports a computer-based form of program documentation in which program forms at various levels of abstraction can have attribute/value pairs attached to any of their granules (granules being well-formed program units of any size such as constants, variables, operators, expressions, statements, blocks, and modules) and in which the attributes may be selectively viewed and queried to suit the needs of different audiences.(4) The notion of attribute/value attachment to granules of program forms also supplies the principal mechanism for promoting a high degree of environment integration. By attaching to program granules such attributes as clocks, counters, units of programmer and system resources spent, version descriptions, access controls, descriptions of tests passed, task schedule data, computer sizing estimates, and so on, smooth integration between the activities of designers, managers, testers, maintainers, programmers, and documenters can be achieved, and environment tools can cooperate with each other conveniently.(5) Arcturus supports an advanced programmer's workstation, an interactive programmer's notebook, and extensive software management support tools.In the framework of the Arcturus effort, we have attempted to rethink afresh issues of epistemology related to the programming process that impact documentation, fault diagnosis, maintenance, training, and software upgrade, so that the design of Arcturus will reflect the relationships between the different kinds of expertise that are required in the programming process. We are also attempting to formulate theories of documentation, debugging, and maintenance to guide the development of computer-based support capabilities that assist in the performance of these activities.In this context, this paper contains preliminary, tentative expositions of background philosophy and rationale that guide our present thinking about Arcturus
Asteroids Were Born Big
How big were the first planetesimals? We attempt to answer this question by
conducting coagulation simulations in which the planetesimals grow by mutual
collisions and form larger bodies and planetary embryos. The size frequency
distribution (SFD) of the initial planetesimals is considered a free parameter
in these simulations, and we search for the one that produces at the end
objects with a SFD that is consistent with asteroid belt constraints. We find
that, if the initial planetesimals were small (e.g. km-sized), the final SFD
fails to fulfill these constraints. In particular, reproducing the bump
observed at diameter D~100km in the current SFD of the asteroids requires that
the minimal size of the initial planetesimals was also ~100km. This supports
the idea that planetesimals formed big, namely that the size of solids in the
proto-planetary disk ``jumped'' from sub-meter scale to multi-kilometer scale,
without passing through intermediate values. Moreover, we find evidence that
the initial planetesimals had to have sizes ranging from 100 to several 100km,
probably even 1,000km, and that their SFD had to have a slope over this
interval that was similar to the one characterizing the current asteroids in
the same size-range. This result sets a new constraint on planetesimal
formation models and opens new perspectives for the investigation of the
collisional evolution in the asteroid and Kuiper belts as well as of the
accretion of the cores of the giant planets.Comment: Icarus (2009) in pres
Automatic Metro Map Layout Using Multicriteria Optimization
This paper describes an automatic mechanism for drawing metro maps. We apply multicriteria optimization to find effective placement of stations with a good line layout and to label the map unambiguously. A number of metrics are defined, which are used in a weighted sum to find a fitness value for a layout of the map. A hill climbing optimizer is used to reduce the fitness value, and find improved map layouts. To avoid local minima, we apply clustering techniques to the map the hill climber moves both stations and clusters when finding improved layouts. We show the method applied to a number of metro maps, and describe an empirical study that provides some quantitative evidence that automatically-drawn metro maps can help users to find routes more efficiently than either published maps or undistorted maps. Moreover, we found that, in these cases, study subjects indicate a preference for automatically-drawn maps over the alternatives
PyCUDA and PyOpenCL: A Scripting-Based Approach to GPU Run-Time Code Generation
High-performance computing has recently seen a surge of interest in
heterogeneous systems, with an emphasis on modern Graphics Processing Units
(GPUs). These devices offer tremendous potential for performance and efficiency
in important large-scale applications of computational science. However,
exploiting this potential can be challenging, as one must adapt to the
specialized and rapidly evolving computing environment currently exhibited by
GPUs. One way of addressing this challenge is to embrace better techniques and
develop tools tailored to their needs. This article presents one simple
technique, GPU run-time code generation (RTCG), along with PyCUDA and PyOpenCL,
two open-source toolkits that support this technique.
In introducing PyCUDA and PyOpenCL, this article proposes the combination of
a dynamic, high-level scripting language with the massive performance of a GPU
as a compelling two-tiered computing platform, potentially offering significant
performance and productivity advantages over conventional single-tier, static
systems. The concept of RTCG is simple and easily implemented using existing,
robust infrastructure. Nonetheless it is powerful enough to support (and
encourage) the creation of custom application-specific tools by its users. The
premise of the paper is illustrated by a wide range of examples where the
technique has been applied with considerable success.Comment: Submitted to Parallel Computing, Elsevie
Design, Commissioning and Performance of the PIBETA Detector at PSI
We describe the design, construction and performance of the PIBETA detector
built for the precise measurement of the branching ratio of pion beta decay,
pi+ -> pi0 e+ nu, at the Paul Scherrer Institute. The central part of the
detector is a 240-module spherical pure CsI calorimeter covering 3*pi sr solid
angle. The calorimeter is supplemented with an active collimator/beam degrader
system, an active segmented plastic target, a pair of low-mass cylindrical wire
chambers and a 20-element cylindrical plastic scintillator hodoscope. The whole
detector system is housed inside a temperature-controlled lead brick enclosure
which in turn is lined with cosmic muon plastic veto counters. Commissioning
and calibration data were taken during two three-month beam periods in
1999/2000 with pi+ stopping rates between 1.3*E3 pi+/s and 1.3*E6 pi+/s. We
examine the timing, energy and angular detector resolution for photons,
positrons and protons in the energy range of 5-150 MeV, as well as the response
of the detector to cosmic muons. We illustrate the detector signatures for the
assorted rare pion and muon decays and their associated backgrounds.Comment: 117 pages, 48 Postscript figures, 5 tables, Elsevier LaTeX, submitted
to Nucl. Instrum. Meth.
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