scholarly journals SPECIAL CONSIDERATION ON THE DESIGN OF AN LNG HARBOR

1974 ◽  
Vol 1 (14) ◽  
pp. 150
Author(s):  
Bernard Le Mehaute
Keyword(s):  
Interest Rates ◽  
Waiting Time ◽  
Closed Loop ◽  
Waiting Times ◽  
Single Point ◽  
Open Loop ◽  
Loop Theory ◽  
Cryogenic Pump ◽  
Optimum Solution ◽  
The Cost

One of the primary considerations in the design of an LNG harbor is safety, requiring berths to be separated by large distance and well protected from the outside wave agitation. Therefore, LNG harbors require expensive structures established as close as possible to the liquefaction plant (while crude tankers may be served by relatively much cheaper, single point mooring servers in deeper water). The cost of waiting time for the very expensive LNG ships has to be weighted against the cost of the additional berths and structures. (A 125, 000 m-^ LNG ships costs $2000/hour. ) The present paper describes the results of a study in which the optimum solution has been obtained by comparing these costs. The number of options is characterized by the number of berths. The cost to be added to the cost of construction of the berths includes an additional length of breakwater and additional dredging, plus the costs of financing during construction and the cost of maintenance. The waiting time for the LNG ship is generally determined, based on the classical Erlang formula for quelng theory. It is recalled that this formula is developed for an open loop. A closed loop theory has been specially developed for the present problem (since LNG ships will most probably operate between two well-defined harbors). The waiting times are 15 to 20% smaller than given by the closed loop theory. A comparison between single berth and double berth is examined. The effect of the rate of filling which is a function of the cryogenic pump capacity (or size of ship depending upon the dominating controlling factor) is analyzed. Finally, the sensitivity of the recommended solution as a function of the interest rates--examined in view of current economic uncertainties--is also investigated. The final recommendation for the design of the harbor, based on the prevailing factors, is the optimum economic solution.

Model Predictive Control and Controller Parameter Optimisation of Combustion Instabilities

2019 ◽  
Vol 36 (2) ◽  
pp. 185-194 ◽  
Author(s):  
I. Yazar ◽  
F. Caliskan ◽  
R. Vepa
Keyword(s):  
Model Predictive Control ◽  
Predictive Control ◽  
Closed Loop ◽  
Combustion Process ◽  
Open Loop ◽  
Loop Model ◽  
Parameter Optimisation ◽  
Direct Adaptive Control ◽  
The Cost ◽  
Adaptive Control Algorithm

Abstract In this paper the application of model predictive control (MPC) to a two-mode model of the dynamics of the combustion process is considered. It is shown that the MPC by itself does not stabilize the combustor and the control gains obtained by applying the MPC algorithms need to be optimized further to ensure that the phase difference between the two modes is also stable. The results of applying the algorithm are compared with the open loop model amplitude responses and to the closed loop responses obtained by the application of a direct adaptive control algorithm. It is shown that the MPC coupled with the cost parameter optimisation proposed in the paper, always guarantees the closed loop stability, a feature that may not always be possible with an adaptive implementations.

Cost of Waiting, Risk, and Individual Action: The Case of Public Housing

1984 ◽  
Vol 2 (3) ◽  
pp. 307-324 ◽  
Author(s):  
K G Willis
Keyword(s):  
Public Housing ◽  
Waiting Time ◽  
Risk Premium ◽  
Time Preference ◽  
Waiting Times ◽  
Individual Action ◽  
Alternative Housing ◽  
Time Estimates ◽  
Time Preference Rate ◽  
The Cost

In this paper the concept of waiting time for public housing is explored; the individual's decisionmaking process on whether to join the housing queue is modeled; how long he/she is prepared to wait for public housing is assessed; a methodology to evaluate the cost of this waiting time is proposed; and estimates of some likely values of this cost are made. The cost of waiting is of more than esoteric interest, impinging on several questions of policy, such as the use of waiting times as indicators in assessing need, the sale of council housing, and the efficiency of a nonprice method of resource allocation. The model predicts the maximum length of time a person will be prepared to wait, given his/her life expectancy in the authority's house, the relative cost to the person of alternative housing, and his/her time-preference rate. Risk preferences are also incorporated to assess the ‘risk premium’: The extra cost a person would sacrifice to be certain of obtaining public housing at a specified time. Estimates of the cost of waiting are derived from the model and also from a questionnaire survey of housing waiting-list applicants in North Tyneside Metropolitan Borough.

scholarly journals Virtual fracture clinic delivers British Orthopaedic Association compliance

2017 ◽  
Vol 99 (1) ◽  
pp. 51-54 ◽  
Author(s):  
J Holgate ◽  
S Kirmani ◽  
B Anand
Keyword(s):  
Emergency Department ◽  
Closed Loop ◽  
Waiting Times ◽  
District General Hospital ◽  
Fracture Clinic ◽  
Mean Waiting Time ◽  
The Cost ◽  
Pro Forma ◽  
Virtual Fracture Clinic ◽  
British Orthopaedic Association

INTRODUCTION The British Orthopaedic Association recommends that patients referred to fracture clinic are thereafter reviewed within 72 hours. With the aim of improving care by seeking to meet this target, waiting times for fracture clinic appointments in a district general hospital were audited prospectively against this national guideline, with the intervening implementation of a virtual fracture clinic. MATERIALS AND METHODS The study was conducted as a prospective closed-loop audit in which the second cycle took place several months after a change in the clinical pathway for all referrals from the emergency department to fracture clinic. Data were gathered in real-time via a pro forma during fracture clinic consultations. RESULTS The first cycle demonstrated a non-compliant mean waiting time of 10.7 days, with 6% of patients being seen within the 72-hour target. Following the implementation of the virtual fracture clinic, the second cycle found that all patients were reviewed within the 72-hour target (mean 1.3 days). DISCUSSION The improvement in performance was delivered with no increase in clinic capacity. The cost of implementation was negligible. CONCLUSION A simple virtual fracture clinic model delivered a significant reduction in waiting times and achieved compliance with the British Orthopaedic Association guideline. Similar results could be achieved in subsequent deployment elsewhere in the NHS.

scholarly journals Private general paediatric care availability in Melbourne

2017 ◽  
Vol 41 (1) ◽  
pp. 63 ◽  
Author(s):  
Marina Kunin ◽  
Amy R. Allen ◽  
Caroline Nicolas ◽  
Gary L. Freed
Keyword(s):  
Waiting Time ◽  
Waiting Times ◽  
Metropolitan Region ◽  
Specialist Care ◽  
Paediatric Care ◽  
Average Potential ◽  
General Paediatrician ◽  
Appointment Availability ◽  
The Cost ◽  
Potential Maximum

Objective The aims of the present study were to determine the actual availability of private general paediatric appointments in the Melbourne metropolitan region for children with non-urgent chronic illnesses and the cost of such care. Methods A ‘secret shopper’ method was used. Telephone calls were made to a random sample of 47 private paediatric clinics. A trained research assistant posed as a parent, requesting the first available appointment with a specific paediatrician. Data regarding appointment availability, total potential charges and net charges after the Medicare rebate were collected. Results Appointments were available in 79% (n = 37) of clinics, with 72% (n = 34) able to offer an appointment with the requested general paediatrician. The number of days until available appointments varied from same day appointments to a wait of 124 days, with an average wait of 33 days. Of practices that provided information about the appointment cost (n = 42), five bulk-billed for the consultation, whereas the remainder (n = 37) were fee-paying clinics. The potential maximum charge for an initial consultation in the fee-paying clinics ranged from A$177 to A$430, with an average cost of A$279. The potential maximum out-of-pocket cost for patients ranged from A$40 to A$222, with an average out-of-pocket cost of A$128. Conclusions Private paediatric care in the Melbourne metropolitan region is generally available. The out-of-pocket cost of private paediatric out-patient care may present a potential economic barrier for some families. What is known about the topic? In Australia, out-of-pocket expenses for private specialist care are not covered by private health insurance. There are no data available on the actual cost of private paediatric consultations that are based on real-time assessments. Data collected in 1998 suggested that the average waiting time for a first standard consultation with a general paediatrician in a private room was 14.1 days. There are no recent empirical data on appointment availability and waiting time for appointments with general paediatricians in Australia. What does this paper add? There is high availability of paediatric consultations in the private sector. Waiting times for an appointment vary considerably from same day appointments to a wait of 124 days, with an average wait of 33 days. The cost of a private paediatric consultation in Australia to the patient is considerable, with an average potential maximum up-front charge for an initial consultation of A$279 and an average potential maximum out-of-pocket cost of A$128. What are the implications for practitioners? Data on the availability and cost of private paediatric consultations are imperative to formulate evidence-informed policy and better understand variations in the availability of public and private care.

On closed-loop equilibrium strategies for mean-field stochastic linear quadratic problems

2020 ◽  
Vol 26 ◽  
pp. 41
Author(s):  
Tianxiao Wang
Keyword(s):  
Optimal Control ◽  
Closed Loop ◽  
Optimal Control Problems ◽  
Mean Field ◽  
Open Loop ◽  
Time Inconsistency ◽  
Control Problems ◽  
Linear Quadratic ◽  
Linear Quadratic Optimal Control ◽  
Equilibrium Strategies

This article is concerned with linear quadratic optimal control problems of mean-field stochastic differential equations (MF-SDE) with deterministic coefficients. To treat the time inconsistency of the optimal control problems, linear closed-loop equilibrium strategies are introduced and characterized by variational approach. Our developed methodology drops the delicate convergence procedures in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. When the MF-SDE reduces to SDE, our Riccati system coincides with the analogue in Yong [Trans. Amer. Math. Soc. 369 (2017) 5467–5523]. However, these two systems are in general different from each other due to the conditional mean-field terms in the MF-SDE. Eventually, the comparisons with pre-committed optimal strategies, open-loop equilibrium strategies are given in details.

Comparison of Dc-Dc SEPIC, CUK and Flyback Converters Based LED Drivers

2020 ◽  
pp. 99-107
Author(s):  
Erdal Sehirli
Keyword(s):  
Integrated Circuit ◽  
Closed Loop ◽  
Input Voltage ◽  
Open Loop ◽  
Current Sensor ◽  
Switching Frequency ◽  
Led Driver ◽  
Advantages And Disadvantages ◽  
Led Drivers ◽  
Conduction Mode

This paper presents the comparison of LED driver topologies that include SEPIC, CUK and FLYBACK DC-DC converters. Both topologies are designed for 8W power and operated in discontinuous conduction mode (DCM) with 88 kHz switching frequency. Furthermore, inductors of SEPIC and CUK converters are wounded as coupled. Applications are realized by using SG3524 integrated circuit for open loop and PIC16F877 microcontroller for closed loop. Besides, ACS712 current sensor used to limit maximum LED current for closed loop applications. Finally, SEPIC, CUK and FLYBACK DC-DC LED drivers are compared with respect to LED current, LED voltage, input voltage and current. Also, advantages and disadvantages of all topologies are concluded.

scholarly journals Interhospital referral of colorectal cancer patients: a Dutch population-based study

2021 ◽  
Author(s):  
A. K. Warps ◽  
◽  
M. P. M. de Neree tot Babberich ◽  
E. Dekker ◽  
M. W. J. M. Wouters ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Cancer Patients ◽  
Waiting Time ◽  
Secondary Care ◽  
Advanced Disease ◽  
Waiting Times ◽  
Tertiary Care ◽  
Disease Stage ◽  
Colorectal Cancer Patients ◽  
Tertiary Care Hospitals

Abstract Purpose Interhospital referral is a consequence of centralization of complex oncological care but might negatively impact waiting time, a quality indicator in the Netherlands. This study aims to evaluate characteristics and waiting times of patients with primary colorectal cancer who are referred between hospitals. Methods Data were extracted from the Dutch ColoRectal Audit (2015-2019). Waiting time between first tumor-positive biopsy until first treatment was compared between subgroups stratified for referral status, disease stage, and type of hospital. Results In total, 46,561 patients were included. Patients treated for colon or rectal cancer in secondary care hospitals were referred in 12.2% and 14.7%, respectively. In tertiary care hospitals, corresponding referral rates were 43.8% and 66.4%. Referred patients in tertiary care hospitals were younger, but had a more advanced disease stage, and underwent more often multivisceral resection and simultaneous metastasectomy than non-referred patients in secondary care hospitals (p<0.001). Referred patients were more often treated within national quality standards for waiting time compared to non-referred patients (p<0.001). For referred patients, longer waiting times prior to MDT were observed compared to non-referred patients within each hospital type, although most time was spent post-MDT. Conclusion A large proportion of colorectal cancer patients that are treated in tertiary care hospitals are referred from another hospital but mostly treated within standards for waiting time. These patients are younger but often have a more advanced disease. This suggests that these patients are willing to travel more but also reflects successful centralization of complex oncological patients in the Netherlands.

scholarly journals Sensuator: A Hybrid Sensor–Actuator Approach to Soft Robotic Proprioception Using Recurrent Neural Networks

Actuators ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 30
Author(s):  
Pornthep Preechayasomboon ◽  
Eric Rombokas
Keyword(s):  
Neural Networks ◽  
Recurrent Neural Networks ◽  
Linear Models ◽  
Open Loop ◽  
Proof Of Concept ◽  
State Estimator ◽  
Loop Control ◽  
Practical Applications ◽  
Soft Actuator ◽  
The Cost

Soft robotic actuators are now being used in practical applications; however, they are often limited to open-loop control that relies on the inherent compliance of the actuator. Achieving human-like manipulation and grasping with soft robotic actuators requires at least some form of sensing, which often comes at the cost of complex fabrication and purposefully built sensor structures. In this paper, we utilize the actuating fluid itself as a sensing medium to achieve high-fidelity proprioception in a soft actuator. As our sensors are somewhat unstructured, their readings are difficult to interpret using linear models. We therefore present a proof of concept of a method for deriving the pose of the soft actuator using recurrent neural networks. We present the experimental setup and our learned state estimator to show that our method is viable for achieving proprioception and is also robust to common sensor failures.

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