Preprocessing embedded actions

Some parser generators allow the user to attach actions, consisting of executable code, to syntax rules. Actions are usually in the local programming language, so they are simply copied into the generated parser. However, we show two situations in which it is convenient to allow actions to be in a different notation. A preprocessor is used to translate such notations into the local programming language. A preprocessor must know where to find actions and how to translate them. We show how these two activities can be programmed separately. Often, the user only has to worry about the second part: once the parser generator is known, the placement of the actions is known as well, so routines for finding actions can be separately compiled and linked in. Examples in the paper are based on the parser generator Yacc, but the approach is not limited to Yacc, or even to parser generators. Certain compositions of syntax-directed translations can be implemented by preprocessing actions.     

The effect of anodic oxide coatings on the mechanical behavior of niobium and tantalum single crystals

The effect of anodic oxide films on the mechanical behavior of single crystals of niobium and tantalum was investigated. Near room temperature, oxide films cause an increase in strength, in the manner generally observed for face-centered cubic crystals. At lower temperatures, oxide films reduce the yield stress and its temperature dependence and cause serrated flow over an appreciable range of strains. When the oxide films are removed from specimens deformed at lower temperatures, the serrations disappear during subsequent deformation, and the yield stress increases rapidly to that of the uncoated material. A model involving generation and motion of edge dislocations from the oxide-metal interface is used to explain the results.     

Complement-fixing antigen of human sarcomas

Further investigation of the humoral immune responses of patients with sarcoma to their tumors revealed a sarcoma-associated antigen that was readily detected by complement fixation. Circulating levels of antibody to this antigen, tentatively labeled S3, rose markedly after surgical removal of the tumor. Antibody to S3, as to S1 and S2, was highly prevalent in patients with various malignant tumors other than sarcoma.     

A Production–Inventory Problem for an Energy Buy-Back Program

This paper considers a production-inventory problem in which the manufacturer participates in an energy buy-back program, which offers probabilistic opportunities with rewards for not using electricity. That is, the manufacturer will get paid for stopping production to save on electricity. The amount rewarded in a period will depend on the electricity market condition at that time. The market condition in any given period is represented by states: normal (i.e., nonpeak), peak type , peak type , and the reward amount in the period will be, and, respectively. The occurrence of each state in a period is dictated by a known probability distribution. The objective is to determine from the manufacturer's perspective, whether to take such an offer when it arises. Under a mild assumption, we show that in the normal market condition, the production decision is partly a base-stock policy, whereas under peak type condition, the manufacturer, upon accepting the offer, produces according to an policy, where. The numerical experiment demonstrates that the cost savings due to buy-backs can be substantial. It also shows that the always-participating strategy (i.e., the firm shuts down production whenever the buy-back program is activated) can perform much worse than the never-participating strategy.     

Computation of approximate optimal policies in a partially observed inventory model with rain checks

This paper proposes a new methodology to solve partially observed inventory problems. Generally, these problems have infinite-dimensional states that are conditional distributions of the inventory level. Our methodology involves linearizing the state transitions via unnormalized probabilities. It then uses an appropriate functional basis to represent the state. Considering the speed and stability of computations, we choose truncated Chebyshev polynomials as the basis. We use Fast Fourier Transforms along with an appropriate discretization of inventory levels to speed up the computations. These main ideas are blended to obtain an iterative algorithm to solve a partially observed inventory model with rain checks. In this model, the inventory manager (IM) does not know the inventory level when it is positive. Otherwise, the IM fully observes it. This model provides a context to illustrate our methodology, which applies to other such models. Although this model has been studied mathematically in the literature, the use of our algorithm provides a numerical approximation of the optimal order quantities. These are compared to the orders released under a base mean-stock policy, where the IM replaces the unobserved inventory level with its mean and applies the well-known base stock policy. We show numerically that the optimal order quantity is very close to the base mean-stock order quantity, when the variance of the inventory distribution is small. When the mean of the inventory distribution is large, the optimal order quantity is more than the base mean-stock quantity, and it is the other way around when the mean is small or negative. These insights are explained via uncertainty and information effects and their interplay. We expect this interplay to show up in other partially observed inventory models.     

Conformance testing in systems with semicontrollable interfaces

In a conformance testing environment, an implementation under test (iut) communicates with multiple entities. A tester may have differing degrees of control on the interactions between these entities and the iut : directly controllable, semicontrollable, or uncontrollable. Semi-controllable inputs most likely render portions of an IUT untestable. In addition, multiple communicating entities may create race conditions during testing. This paper presents a test generation methodology for systems where the semicontrollable inputs can be generated indirectly. The test sequences obtained from the converted graph fully utilize the semicontrollable inputs (where possible) while avoiding the race conditions. Although, for the most general case, the graph conversion results in a exponentially large number of nodes, practical considerations make the converted graph size feasible. This approach is used to generate tests for mil-std 188-220B. By applying the proposed graph conversion and the race condition elimination techniques, the number of testable state transitions increased from approximately 200 to over 700, which represents a coverage of 95% of the transitions defined in the specification.     

Pebble games for studying storage sharing

Pebble games are played on a directed acyclic graph (dag). Placing a pebble on a vertex may be thought of as entering the value of the subexpression represented by the vertex into accessible storage. In some applications, there are types associated with vertices e.g. some vertices may represent functions, others may represent function values. We are interested in determining if vertices of the same type can share storage. The problem considered is as follows. We are given a labelled dag to be pebbled. A pebble may be placed on a vertex if all sons of the vertex have pebbles—in fact it is legal to move a pebble from a son to a father. Pebbles may be picked up at any time. The objective is to pebble each vertex exactly once. We will be interested in ‘one pebblings of l vertices’ in which there is at most one pebble on vertices with label l, at all times; and ‘stack pebblings of l vertices’ in which the pebbled vertices with label l are along a path, at all times. Results about the existence of such pebblings are presented. The results have applications to testing serializability of database updates, and potential applications to semantics directed compiler generation.     

Artificial neural network simulation of hourly groundwater levels in a coastal aquifer system of the Venice lagoon

Artificial Neural Networks (ANNs) have been successfully employed for predicting and forecasting groundwater levels up to some time steps ahead. In this paper, we present an application of feed forward neural networks (FFNs) for long period simulations of hourly groundwater levels in a coastal unconfined aquifer sited in the Lagoon of Venice, Italy. After initialising the model with groundwater elevations observed at a given time, the developed FNN should able to reproduce water level variations using only the external input variables, which have been identified as rainfall and evapotranspiration. To achieve this purpose, the models are first calibrated on a training dataset to perform 1-h ahead predictions of future groundwater levels using past observed groundwater levels and external inputs. Simulations are then produced on another data set by iteratively feeding back the predicted groundwater levels, along with real external data. The results show that the developed FNN can accurately reproduce groundwater depths of the shallow aquifer for several months. The study suggests that such network can be used as a viable alternative to physical-based models to simulate the responses of the aquifer under plausible future scenarios or to reconstruct long periods of missing observations provided past data for the influencing variables is available.     

Limonia fruit as a food supplement to regulate fluoride‐induced hyperglycaemia and hyperlipidaemia

BACKGROUND: Limonia fruit pulp is edible and used in a number of food preparations. This fruit is also used as a folk medicine to treat various ailments and reportedly possesses antihyperglycaemic and antihyperlipidaemic activities. The purpose of the present study was to examine the potential of Limonia acidissima L. (LA) fruit pulp in regulating the carbohydrate and lipid profiles in fluoride‐exposed rats. RESULTS: Exposure to fluoride (100 mg l^?1 NaF) resulted in significant increases in plasma and hepatic carbohydrate and lipid profiles. Administration of LA fruit powder (2.5, 5 and 10 g kg^?1) in the diet for 4 weeks resulted in significant decreases in plasma glucose and lipid profiles and hepatic glucose‐6‐phosphatase activity and significant increases in hepatic glycogen content and hexokinase activity and plasma high‐density lipoprotein cholesterol. Phytochemical analysis of the LA fruit pulp revealed the presence of fibres, phytosterols, saponins, polyphenols, flavonoids and ascorbic acid. CONCLUSION: Consumption of LA fruit pulp is beneficial in controlling hyperglycaemia and hyperlipidaemia in fluoride‐induced toxicity. Since fibres, phytosterols, saponins, polyphenols, flavonoids and total ascorbic acid are known to influence both carbohydrate and lipid metabolisms, the decline in carbohydrate and lipid levels in LA‐administered fluoride‐exposed rats could be attributed to the phytoconstituents of the fruit. Copyright © 2012 Society of Chemical Industry