A cost effective approach to design of energy efficient residential buildings

The objective of this study is to identify cost-optimal efficiency packages at several levels of building energy savings.A two-story residential building locate...     

Simultaneous characterization of perfluoroalkyl carboxylate, sulfonate, and sulfonamide isomers by liquid chromatography-tandem mass spectrometry

A comprehensive method was developed to simultaneously separate and detect perfluorinated acid (PFA) and PFA-precursor isomers using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A linear perfluorooctyl stationary phase and acidified mobile phase increased separation efficiency, relative to alkyl stationary phases, for the many perfluoroalkyl carboxylate (PFCA), perfluoroalkyl sulfonate (PFSA), and perfluorooctyl sulfonamide (PFOSA) isomers and in combination with their distinct MS/MS transitions allowed full resolution of most isomers in standards. Utilizing the absence of the "9-series" and "0-series" product ions, several perfluorooctane sulfonate (C8F17SO3-, PFOS) isomers were structurally elucidated. In human serum, only perfluorooctane sulfonamide (C8F17SO2NH2, FOSA) and PFOS consisted of significant quantities of branched isomers, whereas PFCAs were predominantly linear. Interferences that coelute with the m/z 499 --> 80 transition of PFOS on alkyl stationary phases were simultaneously separated and identified as taurodeoxycholate isomers, removal of which permitted the use of the more sensitive m/z 80 product ion and a resulting 20-fold decrease in PFOS detection limits compared to the m/z 499 --> 99 transition (0.8 pg versus 20 pg using m/z 80 and 99, respectively). Interferences in human serum which caused a 10-20-fold over-reporting of perfluorohexane sulfonate (C6F13SO3-, PFHxS) concentrations on alkyl stationary phases were also simultaneously separated from linear PFHxS and identified as endogenous steroid sulfates. PFOSA isomers, generated with human microsomes, had different rates of metabolism, suggesting that the perfluoroalkyl branching pattern may affect the biological properties of individual isomers. This fact, and for reasons of improved accuracy and sensitivity, investigators are urged to utilize more efficient separation methods capable of isomer characterization in perfluoroalkyl research.     

Capillary HPLC/QTOF-MS for characterizing complex naphthenic acid mixtures and their microbial transformation

A rapidly expanding oil sands industry in Canada produces and indefinitely stores large volumes of toxic aqueous tailings containing high concentrations of naphthenic acids (NAs), a complex mixture of naturally occurring aliphatic or alicyclic carboxylic acids. Although there is an acknowledged need to reduce the environmental risks posed by NAs, little is understood about their environmental fate due to a lack of appropriate analytical methods. A dilute-and-shoot reversed-phase capillary HPLC/QTOF-MS method was developed that combines high specificity and sensitivity, quantitative capabilities, the ability to detect novel transformation products, and new structural information within each NA isomer class. HPLC separated NAs, based on carbon number, degree of cyclization, and the extent of alkyl branching, and in so doing increased analytical sensitivity up to 350-fold while providing additional specificity compared to infusion techniques. For tailings water, an interlaboratory study revealed many differences in isomer class profiles compared to an established GC/MS method, much of which was attributed to the misclassification of oxidized NAs (i.e., NA + O) by low-resolution GC/MS. HPLC/QTOF-MS enabled the detection of oxidized products in the same chromatographic run, and Van Krevelen diagrams were adapted to visualize the complex data. A marked decrease of retention times was evident in Syncrude tailings water compared to a commercial mixture, suggesting that tailings water is dominated by highly persistent alkyl-substituted isomers. A biodegradation study revealed that tailings water microorganisms preferentially deplete the least alkyl-substituted fraction and may be responsible for the NA profile in aged tailings water.     

Fault-Tolerant Multistage Interconnection Network

In this paper, a new fault-tolerant Banyan (FTB) network design is proposed. The rules to add extra hardware and links to the regular Banyan network in order to get the new FTB network are presented. The work includes a modular design for a new 2×2 switch element that can be configured in different well-defined modes. In case an error occurs in the function of a switch in the FTB network, the switch can be bypassed and other switch in the network replaces its role. The most attractive feature of the new design is that it can maintain the original (regular) Banyan topology in the presence of faults. Consequently, the system performance will not be affected due to the occurrence of tolerable faults in the interconnection network. This feature makes our design different from all fault-tolerant designs. Moreover, multiple faults can be tolerated in the proposed FTB network. The FTB network will be very powerful in safety critical systems and applications where error can lead to catastrophic events.     

Aneurysmal bone cysts of the maxilla: a clinicopathologic review

PURPOSE: This study evaluated the significant differences in clinicopathologic features of aneurysmal bone cyst in the maxilla and mandible. MATERIALS AND METHODS: A search of the literature showed 30 recorded maxillary cases, and these together with one previously unrecorded case formed the basis of the study. RESULTS: There were no differences in the age and sex incidence. Only two patients complained of pain, and no patient complained of tenderness. No patient gave a history of trauma. Swelling was present in virtually every patient. In seven cases, there was tooth mobility or migration of teeth. Two patients complained of paresthesia. Four patients presented with proptosis, two of whom complained of diplopia. The radiographic appearance of the aneurysmal bone cyst is suggestive but not diagnostic. CONCLUSION: Although these differences do not enable the clinician to make a definitive diagnosis before biopsy, they have important implications for management.     

Waste minimization in irregular stock cutting

This paper addresses a category of two dimensional NP-hard knapsack problem in which a given convex/non-convex planner items (polygons) have to be cut out of a single convex/non-convex master surface (stock). This cutting process is found in many industrial applications such as sheet metal processes, home-textile, garment, wood, leather and paper industries. An approach is proposed to solve this problem, which depends on the concept of the difference between the area of a collection of polygons and the area of their convex hull. The polygon assignment inside the stock is subjected to feasibility tests to avoid overlapping, namely, angle test, bound test, point inclusion and polygon intersection test. An iterative scheme is used to generate different polygon placements while optimizing the objective function. Computer software is developed to solve and optimize the problem under consideration. Few examples are conducted for different combinations of convex, non-convex items and stocks. Well-known benchmark problems from the literature are tested and compared with our approach. The results of our algorithm have an interesting computational time and can compete with the results of previous work in some particular problems. The computational performance of the developed software indicates the efficiency of the algorithm for solving 2-D irregular cutting of non-convex polygons out of non-convex stock.     

Load Management in Loosely Coupled Multiprocessor Systems

Scheduling is a typical technique used to distribute the load in multiprocessor systems. Usually, the manager(dispatcher or operating system)schedule the tasks so that the average finish time is minimized. Constraints related to the characteristics of the load such as precedence relation, deadline time, etc. must be taken into consideration. With ever increasing applications of a new paradigm of divisible tasks in image processing and parallel processing, one must concentrate on the characteristics of the system such as processor speed, link speed, and processor interconnection topology when distributing the load. By exploiting queuing theory, we managed to find different bounds on the arrival rate(load) as a function of link speed, processor speed and the size of tasks. A flow control mechanism for different multiprocessor systems with different topologies is embedded in our analysis. Moreover, our model indicates to the design engineers, depending on the traffic intensity, which element(s)of a parallel system has to be upgraded or replaced to meet the new load. This, of course, has to be justified by cost consideration.     

Effect of fault tolerance and communication delay on response time in a multiprocessor system with a bus topology

The effect of interprocessor communication and fault tolerance on the response time of N processors (nodes) interconnected through a bus type communication medium is discussed. Deterministic as well as probabilistic approaches are considered. Four correction methods to handle the unprocessed data by the faulty processor(s) are studied and compared. It is found that the effect of interprocessor communication and fault tolerance on the response time for communication-extensive programs (I/O bound) is more than that for computation-extensive programs (CPU bound). It is also found that the effect of fault tolerance on the response time is significant, and cannot be ignored when evaluating the performance of multiprocessor systems. We have shown that the work presented in this paper for a bus topology can be generalized and readily adopted by other multiprocessor network topologies.     

Applying ANOVA and DOE to study the effect of manganese on the hardness and wear rate of artificially aged Al-4.5wt%Cu alloys

The addition of manganese may constitute an important means for imparting the mechanical properties of Al-4.5wt%Cu alloys that have been artificially aged. The literature, however, comprises conflicting reports on the effect of manganese on these alloys. Thus, this work tries to reach results that are more conclusive by utilizing statistical approaches such as Design of Experiments and the Analysis of Variance. Accordingly, different percentages of manganese additions under different aging times were investigated in this study for their effect on hardness and wear rate. Manganese was added in concentrations of 0.2, 0.4, 0.6, 0.8 and 1wt%. Following the solution treatment, aging was applied for time durations of 1, 2 and 3 h. Aging temperature was held constant at 200 °C. Results showed that Mn concentration and aging time have significant effect on alloy hardness and wear rate.     

Closed form solution for response time of fault tolerant network of processors

Employing the queuing theory, closed form solutions for the response time of a fault tolerant network of processors system based on the primary site approach is obtained. Fault tolerance is achieved in the primary site approach by having the services replicated by the primary at many nodes. All the requests are sent to the primary which, periodically, checkpoints its status on the backup nodes. If the primary fails, one of the backups takes over as primary. Two repair mechanisms are considered to repair faulty nodes in the system: delayed repair and immediate repair. In addition to their closed form formats, the analytical results presented in this paper have several other advantages over those presented in the previous work. First, for immediate repair case, there is no need to solve a set of recursive equations. Secondly, the results reveal much of the characteristics of the system. We studied the effect of checkpointing rate on the system response time and we found a closed form solution for the optimum checkpointing rate, which minimizes the system response time.