Strategic allocation of cyclically calling vessels for multi-terminal container operators

We consider a terminal operator who provides container handling services at multiple terminals within the same port. In this setting, the well-known berth allocation problem can no longer be considered for each terminal in isolation since vessel calls should be spread over the various terminals to avoid peaks and troughs in quay crane utilization, and an allocation of two connecting vessels to different terminals will generate inter-terminal container transport. In this paper, we address the problem of spreading a set of cyclically calling vessels over the various terminals and allocating a berthing and departure time to each of them. The objectives are (1) to balance the quay crane workload over the terminals and over time and (2) to minimize the amount of inter-terminal container transport. We develop a solution approach based on mixed-integer programming that allows to solve real-life instances of the problem within satisfactory time. Additionally, a practical case study is presented based on data from the terminal operator PSA Antwerp who operates multiple terminals in the port of Antwerp, Belgium. The computational results show the cost of the currently agreed schedules, and that relatively small modifications can significantly reduce the required crane capacities and inter-terminal transport.     

Automata with hierarchical control and evolutionary learning

We propose an automata-theoretical framework for structured hierarchical control, in terms of rules and meta-rules, for sequences of moves on a graph. This leads to a notion of a "universal" hierarchically structured automaton mu which can move on a given graph in such a way as to emulate any automaton which moves on that graph in response to inputs. This emulation is achieved via a mapping of the inputs in the given automaton to those of mu, and we think of such a mapping as an encoding of the given automaton. We see in several examples that efficient encodings of graph-search algorithms correspond to their natural hierarchical structure (in terms of rules and meta-rules), and this leads one to a precise notion of the "depth" of an automaton which moves on a given graph. By way of application, we discuss a proposed structure of a series of stochastic neural networks which can learn, by example, to encode a given sequence of moves on a graph, so that the encoding obtained is structurally the "natural" one for the given sequence of moves. Thus, such a learning system would perform both structural pattern recognition (in terms of "patterns" of moves), and encoding based on a desired outcome.     

A distinct role of the queen in coordinated workload and soil distribution in eusocial naked mole-rats

We investigated how group members achieve collective decision-making, by considering individual intrinsic behavioural rules and behavioural mechanisms for maintaining social integration. Using a simulated burrow environment, we investigated the behavioural rules of coordinated workload for soil distribution in a eusocial mammal, the naked mole-rat (Heterocephalus glaber). We tested two predictions regarding a distinct role of the queen, a socially dominant individual in the caste system: the presence of a queen would increase the workload of other caste individuals, and the cues by a queen would affect the soil distribution. In experiment 1, we placed four individuals of various castes from the same colony into an experimental burrow. Workers exhibited the highest frequency of workload compared to other castes. The presence of a queen activated the workload by other individuals. Individuals showed a consistent workload in a particular direction so as to bias the soil distribution. These results suggest that individuals have a consensus on soil distribution and that the queen plays a distinct role. In experiment 2, we placed the odour of a queen in one of four cells and observed its effect on other individuals' workload and soil distribution. Relative to other cells, individuals frequently dug in the queen cell so the amount of soil in the queen cell decreased. These results suggest that queen odour is an important cue in coordinated workload and soil distribution in this species.     

The optimal configuration and workload allocation problem in flexible manufacturing systems

In this article we consider the problem of determining the minimum cost configuration (number of machines and pallets) for a flexible manufacturing system with the constraint of meeting a prespecified throughput, while simultaneously allocating the total workload among the machines (or groups of machines). Our procedure allows consideration of upper and lower bounds on the workload at each machine group. These bounds arise as a consequence of precedence constraints among the various operations and/or limitations on the number or combinations of operations that can be assigned to a machine because of constraints on tool slots or the space required to store assembly components. Earlier work on problems of this nature assumes that the workload allocation is given. For the single-machine-type problem we develop an efficient implicit enumeration procedure that uses fathoming rules to eliminate dominated configurations, and we present computational results. We discuss how this procedure can be used as a building block in solving the problem with multiple machine types.     

Global structure of a DNA three-way junction by solution NMR: towards prediction of 3H fold

Three-way junctions (3H) are the simplest and most commonly occurring branched nucleic acids. They consist of three double helical arms (A to C), connected at the junction point, with or without a number of unpaired bases in one or more of the three different strands. Three-way junctions with two unpaired bases in one strand (3HS2) have a high tendency to adopt either of two alternative stacked conformations in which two of the three arms A, B and C are coaxially stacked, i.e. A/B-stacked or A/C-stacked. Empirical stacking rules, which successfully predict for DNA 3HS2 A/B-stacking preference from sequence, have been extended to A/C-stacked conformations. Three novel DNA 3HS2 sequences were designed to test the validity of these extended stacking rules and their conformational behavior was studied by solution NMR. All three show the predicted A/C-stacking preference even in the absence of multivalent cations. The stacking preference for both classes of DNA 3HS2 can thus be predicted from sequence. The high-resolution NMR solution structure for one of the stacked 3HS2 is also reported. It shows a well-defined local and global structure defined by an extensive set of classical NMR restraints and residual dipolar couplings. Analysis of its global conformation and that of other representatives of the 3H family, shows that the relative orientations of the stacked and non-stacked arms, are restricted to narrow regions of conformational space, which can be understood from geometric considerations. Together, these findings open up the possibility of full prediction of 3HS2 conformation (stacking and global fold) directly from sequence.     

Solution structure of a DNA three-way junction containing two unpaired thymidine bases. Identification of sequence features that decide conformer selection

The solution structure of a DNA three-way junction (3H) containing two unpaired thymidine bases at the branch site (3HT2), was determined by NMR. Arms A and B of the 3HT2 form a quasi-continuous stacked helix, which is underwound at the junction and has an increased helical rise. The unstacked arm C forms an acute angle of approximately 55 degrees with the unique arm A. The stacking of the unpaired thymidine bases on arm C resembles the folding of hairpin loops. From this data, combined with the reported stacking behavior of 23 other 3HS2 s, two rules are derived that together correctly reproduce their stacking preference. These rules predict, from the sequence of any 3HS2, its stacking preference. The structure also suggests a plausible mechanism for structure-specific recognition of branched nucleic acids by proteins.     

A chassis exchange terminal to reduce truck congestion at container terminals

Truck congestion for container terminals seems to be a worldwide unwanted phenomenon. In this paper we present and analyze a chassis exchange terminal concept to reduce the congestion. The terminal works as a kind of extended gate of a group of traditional container terminals. During the night containers are collected from these container terminals using chassis (or trailers). In daytime these containers on chassis are then collected and exchanged with export containers also on chassis. By exchanging the chassis we avoid extra handling of containers. As connecting and disconnecting to a chassis can be done in a short time, the chassis exchange terminal increases handling capacity substantially during peak hours. In this paper we analyze the concept for the Maasvlakte container terminals in Rotterdam. We investigate both the effect on waiting time, as well as the environmental effects.     

A new branch and bound algorithm for loading problems in flexible manufacturing systems

Loading problems in flexible manufacturing systems involve assigning operations for selected part types and their associated tools to machines or machine groups. One of the objectives might be to maximize the expected production rate (throughput) of the system. Because of the difficulty in dealing with this objective directly, a commonly used surrogate objective is the closeness of the actual workload allocation to the continuous workload allocation that maximizes throughput. We test several measures of closeness and discuss correlations between these measures and throughput. Using the best measure, we show how to modify an existing branch and bound algorithm which was developed for the case of equal target workloads for all machine groups to accommodate unequal target workloads. We also develop a new branch and bound algorithm which can be used for both types of problems. The efficiency of the algorithm in finding optimal solutions is achieved through the application of better branching rules and improved dominance results. Computational results on randomly generated test problems indicate that the new algorithm performs well.     

Decision support based automatic container sequencing system using heuristic rules

Container terminals in seaports constitute interfaces between the seaborne transport and transport-over-land of goods in global transport chains. The loading and unloading of containers are performed using quay cranes (QCs), which is the most important equipment for handling servicing vessels at a container terminal. Following tremendous growth in global container transshipments, terminals are facing increasing demand. Terminals at Shanghai are equipped with Tandem Lift which can lift two 40’ containers simultaneously to improve the efficiency of the QCs. A reasonable container combinations of Tandem Lift and container operation sequence are required to improve the servicing of vessels, meanwhile the dual cycling container operation of quay cranes has to be investigated. This paper presents a two-stage mathematical model and two-level heuristic algorithm for planning the container operation sequence using Tandem Lift in a feasible computational time. Based on the proposed methodology, a decision support system, called the Tandem Lift Container Sequence System (TLCSS). A case study of Shanghai Shengdong International Port Company (SSICT) proves that consideration of the container sequence with Tandem Lift dramatically shortens servicing time of vessels with the TLCSS.     

DNA helix-stack switching as the basis for the design of versatile deoxyribosensors

The charge conduction properties of DNA can be harnessed for monitoring the binding of a ligand to its receptor. Two classes of such DNA-based sensors (deoxyribosensors) have been described for the ligand adenosine, each generated by the functional coupling of an adenosine-specific DNA aptamer to a charge-conductive DNA path. Here, we report a systematic investigation of the extent to which the features of such ligand-specific deoxyribosensors can be made universal. We have exploited established rules for DNA helical stacking within three-way helical junctions to design and characterize the properties of deoxyribosensors specific for the amino acid derivative, argininamide. The biochemical detection methods described here should translate easily to direct and rapid measurements of changes in current flow using chip-based methods. The results presented here suggest general directions for the design and assembly of deoxyribosensors specific for any molecular ligand, and describe a novel methodology for investigating helical stacking within DNAs and RNAs of unknown tertiary folding, such as novel ribozymes and deoxyribozymes.     

Insulin Stacking Versus Therapeutic Accumulation: Understanding the Differences

ObjectiveThe build-up in insulin levels following repeated injection of prandial insulin at close intervals— referred to as insulin stacking—can increase the risk of hypoglycemia. With the development of basal insulins with a half-life > 24 hours and a duration of action > 40 hours, clinicians may be concerned about stacking when these long-acting formulations are administered once daily. The objective of this review is to clarify the difference between inappropriate insulin stacking when shorter-acting insulin formulations are repeatedly used to correct hyperglycemia and the appropriate accumulation of long-acting insulin formulations dosed to steady-state pharmacokinetic (PK) profiles.MethodsRelevant literature on insulin stacking, glucose-clamp studies, and clinical studies of insulin, in conjunction with the clinical experience of the authors, were used to present an overview of insulin PK properties and the effects of appropriate and inappropriate dosing intervals on steady-state conditions and likely clinical outcomes.ResultsClinical studies confirm theoretical PK principles showing that unwanted insulin stacking (excessive concentrations) for basal insulin can be avoided by following recommended dosing and titration algorithms. Long-acting basal insulins need more time to reach steady state than shorter-acting basal insulins but then show reduced peak-trough fluctuations, translating into more consistent biologic action over a 24-hour period.ConclusionThe unwanted stacking and consequent hypoglycemia that can occur when correctional doses of rapid-acting insulin are administered at close intervals does not occur when long-acting basal insulins are dosed in appropriate amounts and adjusted at appropriate time intervals (e.g., insulin stacking, insulin administration, diabetes, ultralong duration of action, hypoglycemia every three or more days), allowing for pharmacologic steady-state accumulation. (Endocr Pract. 2014;20:75-83)     

A scheduling problem for a novel container transport system: a case of mobile harbor operation schedule

Mobile Harbor (MH) is a movable floating platform with a container handling system on board so that it can load/discharge containers to/from an anchored container ship in the open sea. As with typical quay crane operation, an efficient schedule for its operation is a key to enhancing its operational productivity. A MH operation scheduling problem is to determine a timed sequence of loading/discharging tasks, assignment of MH units to each task, and their docking position, with an objective of minimizing the makespan of a series of incoming container ships. A mixed integer programming model is formulated to formally define the problem. As a practical solution method to the problem, this paper proposes a rule-based algorithm and a random key based genetic algorithm (rkGA). Computational results show that the rkGA method produces a better-quality solution than the rule-based method, while requiring longer computation time.     

Diversity in hapten recognition: structural study of an anti-cocaine antibody M82G2

Antibodies against cocaine and other drugs of abuse are the basis for diagnostic tests for the presence of those drugs in human serum. The 1.7A resolution crystal structure of the anti-cocaine monoclonal antibody M82G2 in complex with cocaine is presented. This structure determination was undertaken to establish the stereochemical features in the antibody binding site that confer specificity for cocaine, and as part of an ongoing project to understand the rules that govern molecular recognition. The cocaine-binding site can be characterized topologically as a narrow groove on the protein surface. The antibody utilizes water-mediated hydrogen bonding, and cation-pi and stacking (pi-pi) interactions to provide specificity. Comparison with the previously published structure of the anti-cocaine antibody GNC92H2 shows that binding of a small ligand can be achieved in diverse ways, both in terms of a binding site structure/topology and protein-ligand interactions.     

Fast evaluation of internal loops in RNA secondary structure prediction.

MOTIVATION: Though not as abundant in known biological processes as proteins, RNA molecules serve as more than mere intermediaries between DNA and proteins. Research in the last 15 years demonstrates that RNA molecules serve in many roles, including catalysis. Furthermore, RNA secondary structure prediction based on free energy rules for stacking and loop formation remains one of the few major breakthroughs in the field of structure prediction, as minimum free energy structures and related quantities can be computed with full mathematical rigor. However, with the current energy parameters, the algorithms used hitherto suffer the disadvantage of either employing heuristics that risk (though highly unlikely) missing the optimal structure or becoming prohibitively time consuming for moderate to large sequences. RESULTS: We present a new method to evaluate internal loops utilizing currently used energy rules. This method reduces the time complexity of this part of the structure prediction from O(n4) to O(n3), thus reducing the overall complexity to O(n3). Even when the size of evaluated internal loops is bounded by k (a commonly used heuristic), the method presented has a competitive edge by reducing the time complexity of internal loop evaluation from O(k2n2) to O(kn2). The method also applies to the calculation of the equilibrium partition function. AVAILABILITY: Source code for an RNA secondary structure prediction program implementing this method is available at ftp://www.ibc.wustl.edu/pub/zuker/zuker .tar.Z     

Strategies for improving a long-established terminal’s performance: a simulation study of a Turkish container terminal

Due to a long-lasting increase in global trade, only interrupted by the late-2000s economic crisis, container traffic has grown dramatically. As a result, new terminals have opened and existing terminals face much higher container handling than before. In order to meet these challenges, one of the biggest container terminals in Turkey has begun to reconsider its terminal operations and to achieve improvements of its overall logistics performance. Because the factors impacting the terminal’s performance are highly interrelated, a simulation model was developed to analyze the terminal operations, to identify potential bottleneck resources and to highlight directions for the future development of the configuration and the operational control system. For a long-established terminal like the one considered in this study the options for improving the overall performance are limited by the geographical dimensions and by the existing terminal equipment. By use of the simulation model the terminal operations are evaluated under different workload scenarios and alternative configurations are tested in order to support strategic decisions on the terminal’s development.     

On a model of human bioenergetics. II. Maximal power and endurance

The properties of a proposed three component hydraulic model of human bioenergetics are examined in respect of the maximum exertable power and the endurance time for given workloads. An equation expressing the decline in maximal effort during an "all-out" exercise is derived, from which a VO2 time equation can be deduced. In addition a workload versus endurance time equation can be obtained, enabling the prediction of time to exhaustion. The resulting equations are illustrated graphically by means of a numerical example. Model predictions, when compared with experimental results, reveal discrepancies which confirm the rejection of the model, as was suggested in an earlier paper.     

Experimental investigation of an FMS due-date scheduling problem: Evaluation of machine and AGV scheduling rules

Although extensive research has been conducted to solve design and operational problems of automated manufacturing systems, many of the problems still remain unsolved. This article investigates the scheduling problems of flexible manufacturing systems (FMSs). Specifically, the relative performances of machine and automated guided vehicle (AGV) scheduling rules are analyzed against various due-date criteria. First, the relevant literature is briefly reviewed, and then the rules are tested under different experimental conditions by using a simulation model of an FMS. The sensitivity to AGV workload, buffer capacity, and processing-time distribution is also investigated to assess the robustness of the scheduling rules.     

Pre-execution power consumption prediction of computational multithreaded workloads

Power management in large-scale computational environments can significantly benefit from predictive models. Such models provide information about the power consumption behavior of workloads prior to running them. Power consumption depends on the characteristics of both the machine and the workload. However, combinational features such as the cache miss rate cannot be considered due to their unavailability before running the workload. Therefore, pre-execution power modeling requires both machine-independent workload characteristics and workload-independent machine characteristics. In this paper the predictive modeling problem is tackled by the proposal of a two-stage modeling framework. In the first stage, a machine learning approach is taken to predict single-threaded workload power consumption at a specific frequency. The second stage analytically scales this output to any intended thread/frequency configuration. Experimental results show that the proposed approach can yield highly accurate predictions about workload power consumption with an average error of 3.7 % on six different test platforms.     

Do Children Who Move Home and School Frequently Have Poorer Educational Outcomes in Their Early Years at School? An Anonymised Cohort Study

Frequent mobility has been linked to poorer educational attainment. We investigated the association between moving home and moving school frequently and the early childhood formal educational achievement. We carried out a cohort analysis of 121,422 children with anonymised linked records. Our exposure measures were: 1) the number of residential moves registered with a health care provider, and 2) number of school moves. Our outcome was the formal educational assessment at age 6–7. Binary regression modeling was used to examine residential moves within the three time periods: 0 – <1 year; 1 – <4 years and 4 – <6 years. School moves were examined from age 4 to age 6. We adjusted for demographics, residential moves at different times, school moves and birth related variables. Children who moved home frequently were more likely not to achieve in formal assessments compared with children not moving. Adjusted odds ratios were significant for 3 or more moves within the time period 1 –<4 years and for any number of residential moves within the time period 4–<6 years. There was a dose response relationship, with increased odds ratios with increased frequency of residential moves (2 or more moves at 4–<6 years, adjusted odds ratio 1.16 (1.03, 1.29). The most marked effect was seen with frequent school moves where 2 or more moves resulted in an adjusted odds ratio of 2.33 (1.82, 2.98). This is the first study to examine the relationship between residential and school moves in early childhood and the effect on educational attainment. Children experiencing frequent mobility may be disadvantaged and should be closely monitored. Additional educational support services should be afforded to children, particularly those who frequently change school, in order to help them achieve the expected educational standards.     

Helix Capping in RNA Structure

Helices are an essential element in defining the three-dimensional architecture of structured RNAs. While internal basepairs in a canonical helix stack on both sides, the ends of the helix stack on only one side and are exposed to the loop side, thus susceptible to fraying unless they are protected. While coaxial stacking has long been known to stabilize helix ends by directly stacking two canonical helices coaxially, based on analysis of helix-loop junctions in RNA crystal structures, herein we describe helix capping, topological stacking of a helix end with a basepair or an unpaired nucleotide from the loop side, which in turn protects helix ends. Beyond the topological protection of helix ends against fraying, helix capping should confer greater stability onto the resulting composite helices. Our analysis also reveals that this general motif is associated with the formation of tertiary structure interactions. Greater knowledge about the dynamics at the helix-junctions in the secondary structure should enhance the prediction of RNA secondary structure with a richer set of energetic rules and help better understand the folding of a secondary structure into its three-dimensional structure. These together suggest that helix capping likely play a fundamental role in driving RNA folding.