Analysis and Optimization of a Multi-Stage Solar Collector System

1986 ◽  
Vol 108 (3) ◽  
pp. 192-198
Author(s):  
J. M. Gordon ◽  
C. Saltiel
Keyword(s):  
Control Strategies ◽  
Cost Effective ◽  
Constant Load ◽  
Analytic Method ◽  
Climatic Data ◽  
Collector System ◽  
Multi Stage ◽  
Cost Effective Method ◽  
Long Term Performance ◽  
Term Performance

We present an analytic method for predicting the long-term performance of solar energy systems with more than one collector brand (“multi-stage” systems). This procedure enables the designer to determine the most cost-effective method of combining different collector brands for a given load. Although our derivations pertain to solar systems for constant load applications and/or near constant collector operating threshold, they can also be used for conventional multi-pass designs. The problems of excess energy delivery, and of various collector on/off control strategies, are taken into account. Our results are simple closed-form expressions whose evaluation requires readily-available average climatic data, and load and collector characteristics. The analytic method is illustrated by a solved example which shows that significant savings can be realized by combining different collector brands for a given application (multi-staging).

Performance of the full-scale biological nutrient removal plant at Noosa in Queensland, Australia: nutrient removal and disinfection

2001 ◽  
Vol 44 (2-3) ◽  
pp. 57-62 ◽  
Author(s):  
V. Urbain ◽  
P. Wright ◽  
M. Thomas
Keyword(s):  
Nutrient Removal ◽  
Volatile Fatty Acids ◽  
Biological Nutrient Removal ◽  
Effluent Quality ◽  
Quality Guidelines ◽  
Treated Effluent ◽  
Multi Stage ◽  
Low Phosphorus ◽  
Long Term Performance ◽  
Term Performance

Stringent effluent quality guidelines are progressively implemented in coastal and sensitive areas in Australia. Biological Nutrient Removal (BNR) plants are becoming a standard often including a tertiary treatment for disinfection. The BNR plant in Noosa - Queensland is designed to produce a treated effluent with less than 5 mg/l of BOD5, 5 mg/l of total nitrogen, 1 mg/l of total phosphorus, 5 mg/l of suspended solids and total coliforms of less than 10/100 ml. A flexible multi-stage biological process with a pre-fermentation stage, followed by sand filtration and UV disinfection was implemented to achieve this level of treatment. Acetic acid is added for phosphorus removal because: i) the volatile fatty acids (VFA) concentration in raw wastewater varies a lot, and ii) the prefermenter had to be turned off due to odor problems on the primary sedimentation tanks. An endogenous anoxic zone was added to the process to further reduce the nitrate concentration. This resulted in some secondary P-release events, a situation that happens when low nitrate and low phosphorus objectives are targeted. Long-term performance data and specific results on nitrogen removal and disinfection are presented in this paper.

Rail Highway Grade Crossing Roughness Quantitative Measurement Using 3D Technology

2014 ◽  
Author(s):  
Teng (Alex) Wang ◽  
Reginald R. Souleyrette ◽  
Daniel Lau ◽  
Peng Xu
Keyword(s):  
Quantitative Method ◽  
Cost Effective ◽  
Actual Condition ◽  
Subjective Rating ◽  
3D Surface ◽  
Grade Crossing ◽  
Long Term Performance ◽  
Term Performance

Quality of surface is an important aspect affecting both the safety and the performance of at-grade rail-highway crossings. Roughness may increase the risk of crashes for both trains and automobiles. Varying grades in crossing profiles increase the likelihood of high-centered crossing collisions between train and truck [1]. The US DOT Railroad Highway Grade Crossing Handbook [2] suggests that rough surfaces could distract a driver’s attention from oncoming trains and that the unevenness of the crossing could result in a driver losing control of their vehicle resulting in a crash. No quantitative method currently exists to quickly and economically assess the condition of rail crossings in order to evaluate the long term performance of crossings and set a quantitative trigger for their rehabilitation. The conventional method to measure the surface of quality of crossings is based on expert judgment, whereby crossing surfaces are classified as poor, fair or good after an inspector visits and drives over the crossing. However, actual condition of the crossing could be different from the subjective rating. Poor condition rating crossings may not always present the most cost-effective locations for preventive maintenance to lower overall life-cycle costs. Conventional ratings may derive from driving a passenger car of pickup once over the crossing. Effects of various speed, on various vehicles (suspension), and at various places (laterally) cannot be determined or even estimated except at the smoothest of crossings. A quantifiable and extensible procedure is desired. With rapid advances in computer science, 3D sensing and imaging technologies, it seems logical that a cost-effective quantitative method could be developed to determine the need to rehabilitate rail crossings and assess long term performance. Fundamental to the quantification of crossing condition is the acquisition of an accurate 3D surface model of the crossing in its present state. This paper reports on the development of an accurate, low cost and readily deployable sensor capable of rapid collection of this 3D surface. The research is seen as a first step towards automating the crossing inspection process, ultimately leading to the quantification and estimation of future performance of rail crossing.

Experimental study on the performance of light and dense backfills

2011 ◽  
Vol 48 (2) ◽  
pp. 214-225 ◽  
Author(s):  
Sumi Siddiqua ◽  
James Blatz ◽  
Greg Siemens
Keyword(s):  
Mechanical Behaviour ◽  
Cost Effective ◽  
Strain Behaviour ◽  
Triaxial Cell ◽  
Important Approach ◽  
Shear Characteristics ◽  
Long Term Performance ◽  
Term Performance ◽  
Sealing Materials

Numerical modeling is a cost-effective and important approach to examine the long-term performance of engineered materials. However, to identify the appropriate constitutive model for a particular material it is necessary to measure physical properties in a laboratory. Laboratory experiments provide the data from which the input parameters for the selected model can be interpreted. This paper studies the mechanical behaviour of two clay-based sealing materials — light backfill and dense backfill — recommended for use in disposal of nuclear waste in a proposed Canadian repository. Test specimens of light and dense backfills were saturated in a triaxial cell and then subjected to specified isotropic and shearing stress paths to measure consolidation and shear characteristics. The triaxial results are interpreted in a critical state context. The light backfill results suggest that it has similar stress–strain behaviour to a bentonite–sand buffer, which has a similar composition, but different preparation procedures and design requirements. Results from testing of dense backfill indicate that it is a much stiffer and stronger material than light backfill. Dense backfill is expected to provide mechanical support to the used-fuel container and other sealing components of the Canadian repository, and the mechanical behaviour of dense backfill satisfies these requirements.

Pond and wetland treatment

2003 ◽  
Vol 48 (5) ◽  
pp. 1-8 ◽  
Author(s):  
R.H. Kadlec
Keyword(s):  
Temperature Dependence ◽  
Rate Constants ◽  
Cost Effective ◽  
Fecal Coliforms ◽  
First Order ◽  
Loading Rates ◽  
Wetland Treatment ◽  
Long Term Performance ◽  
Term Performance

Wetlands are in use as adjuncts to wastewater treatment lagoons at many north temperate locations. Performance data for 21 systems show median removals of 67, 61, 61, 48 and 99.8% for TSS, BOD, NH4-N, TP and fecal coliforms, respectively. Hydraulic loading rates range from 0.14 to 55 cm/d, areas from 0.02 to 200 ha, and latitudes from 30 to 54°N. Calibrations of first order models with temperature dependence show that rate constants vary from seasonal dependence at low loadings to temperature dependence at high loadings for ammonia. Phosphorus rate constants display seasonal, not temperature effects. BOD and TSS are not affected by season. Wetland rate constants are larger than those for lagoons for all constituents. The optimal winter operating strategy, if hydraulics allow, is partial storage during frozen months, coupled with winter use of the wetlands. The use of FWS wetlands for polishing lagoon effluents is cost effective when land availability is not drastically constrained. Many systems have been in operation long enough to demonstrate sustainable long-term performance. Infiltration beds are potentially a valuable addition to ponds and wetlands.

scholarly journals Audible Feedback Improves Internal Model Strength and Performance of Myoelectric Prosthesis Control

2018 ◽  
Author(s):  
Ahmed W. Shehata ◽  
Erik J. Scheme ◽  
Jonathon W. Sensinger
Keyword(s):  
Feedback Control ◽  
Internal Model ◽  
Control Strategies ◽  
Short Term ◽  
Augmented Feedback ◽  
Myoelectric Prosthesis ◽  
Prosthetic Devices ◽  
Long Term Performance ◽  
Term Performance

AbstractMyoelectric prosthetic devices are commonly used to help upper limb amputees perform activities of daily living, however amputees still lack the sensory feedback required to facilitate reliable and precise control. Augmented feedback may play an important role in affecting both short-term performance, through real-time regulation, and long-term performance, through the development of stronger internal models. In this work, we investigate the potential tradeoff between controllers that enable better short-term performance and those that provide sufficient feedback to develop a strong internal model. We hypothesize that augmented feedback may be used to mitigate this tradeoff, ultimately improving both short and long-term control. We used psychometric measures to assess the internal model developed while using a filtered myoelectric controller with augmented audio feedback, imitating classification-based control but with augmented regression-based feedback. In addition, we evaluated the short-term performance using a multi degree-of-freedom constrained-time target acquisition task. Results obtained from 24 able-bodied subjects show that an augmented feedback control strategy using audio cues enables the development of a stronger internal model than the filtered control with filtered feedback, and significantly better path efficiency than both raw and filtered control strategies. These results suggest that the use of augmented feedback control strategies may improve both short-term and long-term performance.

scholarly journals Porous Fe0/C ceramsites for removal of aqueous Pb(ii) ions: equilibrium, long-term performance and mechanism studies

RSC Advances ◽  
2018 ◽  
Vol 8 (45) ◽  
pp. 25445-25455 ◽  
Author(s):  
Pingfeng Fu ◽  
Xiaofeng Lin ◽  
Zihao Chen
Keyword(s):  
Cost Effective ◽  
Paper Mill ◽  
Paper Mill Sludge ◽  
Long Term Performance ◽  
Term Performance ◽  
Performance And Mechanism

Cost-effective Fe0/C microelectrolysis ceramsites were fabricated from magnetite, coal and paper mill sludge with high long-term performance in the removal of Pb(ii) ions.

Performance-based specifications for pavements

1991 ◽  
Vol 18 (6) ◽  
pp. 1054-1061 ◽  
Author(s):  
P. Kuzyk ◽  
R. C. G. Haas ◽  
R. W. Cockfield
Keyword(s):  
Risk Factors ◽  
Key Words ◽  
Current Practice ◽  
Cost Effective ◽  
Pavement Performance ◽  
Substantial Portion ◽  
Actual Performance ◽  
Long Term Performance ◽  
Term Performance

Pavements represent a very substantial portion of the public's investment in infrastructure. It is essential that this investment be preserved through cost-effective planning, design, and maintenance. One way of achieving this is through the use of long-term performance-based specifications. This paper first describes the current practice for pavement specification. For the most part, these specifications are "recipe" orientated. Very specific requirements are set for procedures, such as compaction, or as constructed properties such as density. With the proposed system, the contractor would be required to warranty the actual performance of the pavement over an extended term. The paper describes the overall scope of the system, its key elements and advantages, and the major risk factors. As well, the measures that can be used to characterize performance and a model for estimating performance are identified. A stochastic formulation of the model is used to present a method of determining the risk to the contractor based on a design example. Finally, the paper explores some of the concerns associated with the implementation of the system and how these concerns might be addressed. Key words: long-term warranties, pavement contracting, pavement performance.

scholarly journals Analysis of the Deviation in a Low-Cost System for Stepless Digital Control of Conventional Lathe Spindle Speeds

2018 ◽  
Vol 9 (1) ◽  
pp. 12 ◽  
Author(s):  
Tadeusz Mikolajczyk ◽  
Tomasz Paczkowski ◽  
Danil Yurievich Pimenov ◽  
Mozammel Mia ◽  
Karali Patra ◽  
...  
Keyword(s):  
Digital Control ◽  
Low Cost ◽  
Cutting Speed ◽  
Cost Effective ◽  
Spindle Speed ◽  
Automated Control ◽  
Electric Motor Drives ◽  
Multi Stage ◽  
Cost Effective Method ◽  
Effective System

A conventional manual lathe electric motor drives the multi-stage gearbox transmitting torque to the spindle so that the workpiece makes contact with the machine tool at a given speed. The cutting speed is proportional to both the diameter of the workpiece and the spindle speed, however, the increments in spindle speed are limited. Manual lathe machines cannot be regulated at the optimum cutting speeds for all diameters. An innovative modernization of the main driveline of a TSB16 manual lathe is proposed in this paper, allowing for a cost-effective system for digital control of spindle speeds using an inverter. The inverter is controlled using an 8-bit AO (analog output) converter with special software developed with Visual Basic. The results of the analysis and various test runs with this new system for automated control of spindle rotation, showed that the required cutting speed can be achieved for any workpiece diameter. The deviation of cutting-speed of the upgraded system for any turning diameter is greatly reduced in comparison with the deviation of cutting-speed of a manual lathe. Finally, tests on this versatile system demonstrated a cost-effective method for modernizing the drive system of conventional lathe machines.

scholarly journals Evaluating Internal Model Strength and Performance of Myoelectric Prosthesis Control Strategies

2017 ◽  
Author(s):  
Ahmed W. Shehata ◽  
Erik J. Scheme ◽  
Jonathon W. Sensinger
Keyword(s):  
Internal Model ◽  
Control Strategies ◽  
Model Development ◽  
Myoelectric Control ◽  
Myoelectric Prosthesis ◽  
And Performance ◽  
Prosthesis Control ◽  
Long Term Performance ◽  
Term Performance

AbstractOngoing developments in myoelectric prosthesis control have provided prosthesis users with an assortment of control strategies that vary in reliability and performance. Many studies have focused on improving performance by providing feedback to the user, but have overlooked the effect of this feedback on internal model development, which is key to improving long-term performance. In this work, the strength of internal models developed for two commonly used myoelectric control strategies: raw control with raw feedback (using a regression-based approach), and filtered control with filtered feedback (using a classifier-based approach), were evaluated using two psychometric measures: trial-by-trial adaptation and just-noticeable-difference. The performance of both strategies was also evaluated using a Schmidt’s style target acquisition task. Results obtained from 24 able-bodied subjects showed that although filtered control with filtered feedback had better short-term performance in path efficiency (p < 0.05), raw control with raw feedback resulted in stronger internal model development (p < 0.05), which may lead to better long-term performance. Despite inherent noise in the control signals of the regression controller, these findings suggest that rich feedback associated with regression control may be used to improve human understanding of the myoelectric control system.

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