scholarly journals Getting Started

2021 ◽  
pp. 11-24
Author(s):  
Guillaume Marois ◽  
Samir KC
Keyword(s):  
Discrete Time ◽  
Microsimulation Model ◽  
Base Population ◽  
Multistate Model ◽  
Set Up

AbstractThis chapter sets the stage before building the microsimulation model. First, we describe proprieties of the microsimulation model that will be built. The model is time-based, discrete-time and stochastic. We then describe properties of a multistate model that will be converted into a microsimulation model and we show how building a synthetic base population that consists of the individuals that will be projected. We finally explain how to set up the workspace in SAS.

scholarly journals Computational Procedures for a Class of GI/D/kSystems in Discrete Time

2009 ◽  
Vol 2009 ◽  
pp. 1-18
Author(s):  
Md. Mostafizur Rahman ◽  
Attahiru Sule Alfa
Keyword(s):  
Discrete Time ◽  
Queue Length ◽  
Computation Time ◽  
Single Server ◽  
The Matrix ◽  
Interarrival Times ◽  
Computational Procedures ◽  
Set Up ◽  
First In First Out ◽  
Service Duration

A class of discrete time GI/D/ksystems is considered for which the interarrival times have finite support and customers are served in first-in first-out (FIFO) order. The system is formulated as a single server queue with new general independent interarrival times and constant service duration by assuming cyclic assignment of customers to the identical servers. Then the queue length is set up as a quasi-birth-death (QBD) type Markov chain. It is shown that this transformed GI/D/1 system has special structures which make the computation of the matrixRsimple and efficient, thereby reducing the number of multiplications in each iteration significantly. As a result we were able to keep the computation time very low. Moreover, use of the resulting structural properties makes the computation of the distribution of queue length of the transformed system efficient. The computation of the distribution of waiting time is also shown to be simple by exploiting the special structures.

scholarly journals Prediction of hospital bed capacity during the COVID− 19 pandemic

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Mieke Deschepper ◽  
Kristof Eeckloo ◽  
Simon Malfait ◽  
Dominique Benoit ◽  
Steven Callens ◽  
...  
Keyword(s):  
Poisson Model ◽  
University Hospital ◽  
Planning Tool ◽  
Multistate Model ◽  
Hospital Data ◽  
Short Term ◽  
Worst Case ◽  
Bed Capacity ◽  
Set Up ◽  
Hospital Wards

Abstract Background Prediction of the necessary capacity of beds by ward type (e.g. ICU) is essential for planning purposes during epidemics, such as the COVID− 19 pandemic. The COVID− 19 taskforce within the Ghent University hospital made use of ten-day forecasts on the required number of beds for COVID− 19 patients across different wards. Methods The planning tool combined a Poisson model for the number of newly admitted patients on each day with a multistate model for the transitions of admitted patients to the different wards, discharge or death. These models were used to simulate the required capacity of beds by ward type over the next 10 days, along with worst-case and best-case bounds. Results Overall, the models resulted in good predictions of the required number of beds across different hospital wards. Short-term predictions were especially accurate as these are less sensitive to sudden changes in number of beds on a given ward (e.g. due to referrals). Code snippets and details on the set-up are provided to guide the reader to apply the planning tool on one’s own hospital data. Conclusions We were able to achieve a fast setup of a planning tool useful within the COVID− 19 pandemic, with a fair prediction on the needed capacity by ward type. This methodology can also be applied for other epidemics.

Money creation and banks’ interest rate setting

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alexey Ponomarenko
Keyword(s):  
Interest Rate ◽  
Design Methodology ◽  
Learning Algorithm ◽  
Microsimulation Model ◽  
Content Type ◽  
Lending Rate ◽  
Potential Case ◽  
Money Creation ◽  
Set Up

Purpose This study aims to examine a potential case of interdependence in loan and deposit interest rate setting. Design/methodology/approach The authors set up a theoretical microsimulation model with endogenous loan interest rate determination via a learning algorithm. Findings The authors show that in certain environments, it may be beneficial for large banks to incorporate information on retail funding costs into the lending rate setting decision. Originality/value The author’s model is based on the realistic money creation mechanism.

scholarly journals Dynamics of a discrete-time system with Z-type control

2020 ◽  
Vol 75 (7) ◽  
pp. 609-620
Author(s):  
Shilpa Garai ◽  
Moumita Garain ◽  
Sudip Samanta ◽  
Nikhil Pal
Keyword(s):  
Discrete Time ◽  
Control Mechanism ◽  
Population Control ◽  
Supporting Evidence ◽  
Discrete Time System ◽  
Predator Prey ◽  
Predator Prey Model ◽  
Prey System ◽  
Set Up ◽  
The Stability

AbstractIn community ecology, the stability of a predator–prey system is a considerably desired issue; as a result, population control of a predator–prey system is very important. The dynamics of continuous-time models with Z-type control is studied earlier. But, the effectiveness of the Z-type control mechanism in a discrete-time set-up is lacking. First, we consider a Lotka–Volterra type discrete-time predator–prey model. We observe that without control, the system exhibits rich dynamical behaviors including chaotic oscillations. We apply the Z-control mechanism in both direct and indirect ways to the system and observe that in both cases, controllers have the property to drive the populations of the system to the desired state. We conduct numerical simulation as supporting evidence of our analytical results.

The Effects of Drying Techniques on Clay-Rich Soil Texture

1974 ◽  
Vol 32 ◽  
pp. 466-467
Author(s):  
T. G. Naymik
Keyword(s):  
Critical Point ◽  
Liquid Nitrogen ◽  
Liquid Nitrogen Temperature ◽  
Drying Methods ◽  
Air Drying ◽  
Freeze Dried ◽  
Critical Point Drying ◽  
Set Up ◽  
The Relationship ◽  
Quartz Grains

Three techniques were incorporated for drying clay-rich specimens: air-drying, freeze-drying and critical point drying. In air-drying, the specimens were set out for several days to dry or were placed in an oven (80°F) for several hours. The freeze-dried specimens were frozen by immersion in liquid nitrogen or in isopentane at near liquid nitrogen temperature and then were immediately placed in the freeze-dry vacuum chamber. The critical point specimens were molded in agar immediately after sampling. When the agar had set up the dehydration series, water-alcohol-amyl acetate-CO2 was carried out. The objectives were to compare the fabric plasmas (clays and precipitates), fabricskeletons (quartz grains) and the relationship between them for each drying technique. The three drying methods are not only applicable to the study of treated soils, but can be incorporated into all SEM clay soil studies.

Evaluation of Freezing Methods by Low Temperature X-Ray Diffraction

1977 ◽  
Vol 35 ◽  
pp. 330-333
Author(s):  
T. Gulik-Krzywicki ◽  
M.J. Costello
Keyword(s):  
Biological Materials ◽  
Molecular Organization ◽  
X Ray Diffraction ◽  
Glass Capillary ◽  
X Ray ◽  
Rate Dependent ◽  
Before And After ◽  
Freeze Etching ◽  
Diffraction Patterns ◽  
Set Up

Freeze-etching electron microscopy is currently one of the best methods for studying molecular organization of biological materials. Its application, however, is still limited by our imprecise knowledge about the perturbations of the original organization which may occur during quenching and fracturing of the samples and during the replication of fractured surfaces. Although it is well known that the preservation of the molecular organization of biological materials is critically dependent on the rate of freezing of the samples, little information is presently available concerning the nature and the extent of freezing-rate dependent perturbations of the original organizations. In order to obtain this information, we have developed a method based on the comparison of x-ray diffraction patterns of samples before and after freezing, prior to fracturing and replication.Our experimental set-up is shown in Fig. 1. The sample to be quenched is placed on its holder which is then mounted on a small metal holder (O) fixed on a glass capillary (p), whose position is controlled by a micromanipulator.

Eels Under Standing Wave Conditions

1982 ◽  
Vol 40 ◽  
pp. 492-495
Author(s):  
O.L. Krivanek ◽  
J. TaftØ
Keyword(s):  
Standing Wave ◽  
Wave Conditions ◽  
Set Up ◽  
A Site ◽  
Complex Crystal

It is well known that a standing electron wavefield can be set up in a crystal such that its intensity peaks at the atomic sites or between the sites or in the case of more complex crystal, at one or another type of a site. The effect is usually referred to as channelling but this term is not entirely appropriate; by analogy with the more established particle channelling, electrons would have to be described as channelling either through the channels or through the channel walls, depending on the diffraction conditions.

Low-Loss Images in a Stem/Tem Microscope

1976 ◽  
Vol 34 ◽  
pp. 496-497 ◽  
Author(s):  
David C. Joy ◽  
Dennis M. Maher
Keyword(s):  
High Resolution ◽  
Surface Topography ◽  
Beam Direction ◽  
Low Loss ◽  
Specimen Holder ◽  
Glancing Angle ◽  
High Resolution Images ◽  
Set Up ◽  
Conventional Manner ◽  
Objective Type

High-resolution images of the surface topography of solid specimens can be obtained using the low-loss technique of Wells. If the specimen is placed inside a lens of the condenser/objective type, then it has been shown that the lens itself can be used to collect and filter the low-loss electrons. Since the probeforming lenses in TEM instruments fitted with scanning attachments are of this type, low-loss imaging should be possible.High-resolution, low-loss images have been obtained in a JEOL JEM 100B fitted with a scanning attachment and a thermal, fieldemission gun. No modifications were made to the instrument, but a wedge-shaped, specimen holder was made to fit the side-entry, goniometer stage. Thus the specimen is oriented initially at a glancing angle of about 30° to the beam direction. The instrument is set up in the conventional manner for STEM operation with all the lenses, including the projector, excited.

UHV-TEM studies of laser-induced damage

1991 ◽  
Vol 49 ◽  
pp. 632-633
Author(s):  
T.S. Savage ◽  
R. Ai ◽  
D. Dunn ◽  
L.D. Marks
Keyword(s):  
Surface Science ◽  
Rapid Heating ◽  
Local Heating ◽  
Routine Practice ◽  
Transmission Electron ◽  
Northwestern University ◽  
Laser Induced Damage ◽  
Set Up ◽  
Focusing Lens ◽  
Diffusion Of Impurities

The use of lasers for surface annealing, heating and/or damage has become a routine practice in the study of materials. Lasers have been closely looked at as an annealing technique for silicon and other semiconductors. They allow for local heating from a beam which can be focused and tuned to different wavelengths for specific tasks. Pulsed dye lasers allow for short, quick bursts which can allow the sample to be rapidly heated and quenched. This short, rapid heating period may be important for cases where diffusion of impurities or dopants may not be desirable.At Northwestern University, a Candela SLL - 250 pulsed dye laser, with a maximum power of 1 Joule/pulse over 350 - 400 nanoseconds, has been set up in conjunction with a Hitachi UHV-H9000 transmission electron microscope. The laser beam is introduced into the surface science chamber through a series of mirrors, a focusing lens and a six inch quartz window.

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