Simultaneous Assignment Research Articles

Sequential versus simultaneous assignment systems and two applications

We study assignment systems where objects are assigned to agents sequentially. Student placement to exam and mainstream schools in the USA and centralized teacher appointment in Turkey are two of many examples. Despite their prevalence in practice, research on sequential systems has been rather limited. We analyze the properties of the systems in use in these places and show that they do not satisfy desirable fairness, welfare, and incentive criteria. It turns out such shortcomings are inherent in more general sequential assignment systems as well. We then analyze preference revelation games associated with various sequential systems including those comprising of combinations of well-known mechanisms.

STOMA: Simultaneous Template Optimization and Mask Assignment for Directed Self-Assembly Lithography With Multiple Patterning

Block copolymer directed self-assembly (DSA) is a promising technique to print contacts/vias for the 10 nm technology node and beyond. By using hybrid lithography that incorporates DSA with multiple patterning, multiple masks are used to print the DSA templates and then the templates can be used to guide the self-assembly of the block copolymer. In this paper, we propose approaches to solve the simultaneous template optimization and mask assignment problem for DSA with multiple patterning. We verified in experiments that our approaches remarkably outperform the state-of-the-art work in reducing the manufacturing cost.

A genetic algorithm based on spatiotemporal conflict between continuous berth-allocation and time-varying specific crane assignment

ABSTRACTBerths and quay cranes (QCs) are two important resources in container terminals. Although good planning can shorten ship turnaround times, berths and QCs are interdependent. In the handling process, the number of QCs assigned to a ship may vary because of other ships berthing or departing. This variation, in turn, affects the QCs’ efficiency and the ship handling time, thus affecting the following ships’ berth–QC planning. In this article, a new mixed-integer programming model for simultaneous continuous berth-allocation and time-varying specific QC assignment is established. Furthermore, a genetic algorithm based on spatiotemporal conflict is designed for the model. Numerical experiments show that the proposed method can provide a reasonable solution for such an NP-hard problem in a reasonable time. In addition, the important parameters affecting the results are analysed.

Batch‐based security‐aware spectrum sharing with simultaneous assignment decisions in time‐critical IoT networks with cognitive radio capabilities

AbstractCognitive radio (CR) is considered as a key enabling communication technology that offers efficient wireless connectivity to Internet of Things (IoT) devices. Its integration with the future 5G architecture is expected to advance the IoT paradigm. Security attacks can severely degrade the performance of such CR‐based IoT (CRIoT) networks. The effect of security attacks can be reduced by implementing defensive approaches. However, such solutions come at the expense of degrading spectrum efficiency and consuming more network resources. In this paper, we investigate the spectrum sharing and access problem in a multidevice single‐transceiver CRIoT network with time‐critical applications under jamming attacks. Our main goal is to maximize the number of simultaneously served IoT devices over all available idle channels while ensuring delay requirement, hardware, link quality, security attacks, and spectrum utilization constraints. This problem is formulated as a total unimodular binary linear programming, which is shown to be solvable in polynomial time. Unlike most of previous security‐aware channel assignment solutions that conduct the channel assignment sequentially, our solution simultaneously provides secured distributed channel‐assignment decisions for multiple CRIoT links (batching method). Batching can be realized through an admission control stage for CR IoT devices to announce their control packets. Simulation results reveal that our solution significantly improves network performance compared to previous security‐aware schemes.

Synthesis of Intellectual Parallel Manipulator with Two Degrees of Freedom

A manipulating robot, which has the given lows of motions of the grippers and actuators, is called an intellectual robot (MR). Setting the lows of motions of the actuators is simplified the control system and improved the dynamics of the MR. In the simultaneous assignment of the motion lows of the grippers and the actuators, the intellectual MR work under certain structure diagrams and geometrical parameters of links. In this paper, describe the methods of structural and dimensional synthesis of the intellectual manipulator with 2 DOF.

Optimal boat–barge convoy formation and freight assignment in inland waterways freight transportation

This paper addresses the problem of boat–barge convoy dispatch that arises in the simultaneous assignment of freight to and the formation of boat–barge convoys in inland waterways transportation. Normally, the dispatch type of problem under consideration in this paper is faced daily in inland waterways transportation networks, for which there does not exist as yet a general mathematical programming model. In this paper, the problem is formulated within a binary linear programming modelling framework, which is applicable to inland waterways networks of any configuration. The mathematical model is applied to a real-world case, which is encountered in inland waterways transportation in the Amazon region in Brazil, so as to illustrate the use of the model in practice. The global optimal solution that is obtained results in substantial cost reduction, in comparison with the present dispatch policy, which is based on past experience. Consequently, the mathematical model has been adopted by the company as a basis for decision support in boat–barge convoy formation and dispatch within its enterprise planning system.

Bifurcatriol, a New Antiprotozoal Acyclic Diterpene from the Brown Alga Bifurcaria bifurcata.

Linear diterpenes that are commonly found in brown algae are of high chemotaxonomic and ecological importance. This study reports bifurcatriol (1), a new linear diterpene featuring two stereogenic centers isolated from the Irish brown alga Bifurcaria bifurcata. The gross structure of this new natural product was elucidated based on its spectroscopic data (IR, 1D and 2D-NMR, HRMS). Its absolute configuration was identified by experimental and computational vibrational circular dichroism (VCD) spectroscopy, combined with the calculation of 13C-NMR chemical shielding constants. Bifurcatriol (1) was tested for in vitro antiprotozoal activity towards a small panel of parasites (Plasmodium falciparum, Trypanosoma brucei rhodesiense, T. cruzi, and Leishmania donovani) and cytotoxicity against mammalian primary cells. The highest activity was exerted against the malaria parasite P. falciparum (IC50 value 0.65 μg/mL) with low cytotoxicity (IC50 value 56.6 μg/mL). To our knowledge, this is the first successful application of VCD and DP4 probability analysis of the calculated 13C-NMR chemical shifts for the simultaneous assignment of the absolute configuration of multiple stereogenic centers in a long-chain acyclic natural product.

UN-GHS — Physical hazard classifications of chemicals: A critical review of combinations of hazard classes

One of the fundamental principles of the UN-GHS (Globally Harmonized System of Classification and Labelling of Chemicals) is that all hazards of a chemical should be assigned and communicated. There is no general prioritization of hazards in the sense that certain hazard classes are not applicable if another one has been assigned. In contrast to health and environmental hazards, there are physical or chemical factors which preclude certain combinations of physical hazard classes. So far, there is no common understanding as to which combinations are relevant and which not. For example, should a pyrophoric liquid be classified as flammable liquid in addition, or is this redundant and unnecessary? In the course of the implementation of the GHS by countries or sectors and the actual application by industry all over the world, such questions become more and more important. This publication systematically discusses all combinations of the UN-GHS physical hazard classes and assesses them with regard to the relevance of possible simultaneous assignment to a chemical. For many of the combinations an unambiguous decision based on the GHS alone is not possible, thus confirming that the question which physical hazard classes might be assigned simultaneously to a chemical is not trivial. As one more milestone on the path to a globally harmonized system for the classification of hazardous chemicals, this should be discussed and ultimately solved on a global basis. It is the hope that this publication might serve as an impetus for such discussions.

Theoretical Studies of the Electronic Absorption Spectra of Thiamin Diphosphate in Pyruvate Decarboxylase.

Electronic absorption spectra are oftentimes used to identify reaction intermediates or substrates/products in enzymatic systems, as long as absorption bands can be unequivocally assigned to the species being studied. The latter task is far from trivial given the transient nature of some states and the complexity of the surrounding environment around the active site. To identify unique spectral fingerprints, controlled experiments with model compounds have been used in the past, but even these can sometimes be unreliable. Circular dichroism (CD) and ultraviolet-visible spectra have been tools of choice in the study of the rich chemistry of thiamin diphosphate-dependent enzymes. In this study, we focus on the Zymomonas mobilis pyruvate decarboxylase, and mutant analogues thereof, as a prototypical representative of the thiamin diphosphate (ThDP) enzyme superfamily. Through the use of electronic structure methods, we analyze the nature of electronic excitations in the cofactor. We find that all the determining CD bands around the 280-340 nm spectral range correspond to charge-transfer excitations between the pyrimidine and thiazolium rings of ThDP, which, most likely, is a general property of related ThDP-dependent enzymes. While we can confirm the assignments of previously proposed bands to chemical states, our calculations further suggest that a hitherto unassigned band of enzyme-bound ThDP reports on the ionization state of the canonical glutamate that is required for cofactor activation. This finding expands the spectroscopic "library" of chemical states of ThDP enzymes, permitting a simultaneous assignment of both the cofactor ThDP and the activating glutamate. We anticipate this finding to be helpful for mechanistic analyses of related ThDP enzymes.

A Batch-Based MAC Design With Simultaneous Assignment Decisions for Improved Throughput in Guard-Band-Constrained Cognitive Networks

The adjacent channel interference (ACI) resulting from imperfect filtering can severely degrade the performance of any wireless communication system. Despite this fact, most of previously proposed medium access control (MAC) protocols for cognitive radio networks (CRNs) were designed while ignoring the effects of ACI (assuming ideal filtering). The effect of ACI can be reduced by introducing guard bands (GBs). However, this solution comes at the expense of degrading spectrum efficiency. In this paper, we develop an efficient GB-aware MAC protocol that attempts at maximizing network throughput while improving fairness in CRNs. Unlike most of previously proposed GB-aware MAC protocols that perform channel assignment sequentially, our MAC performs the channel assignment for multiple CR links simultaneously (the so-called batch method). Batching enables concurrent channel assignment for multiple CR links, which consequently allows for concurrent data transmissions. Batching can be realized by introducing an admission control phase for CR users to share their control information. The batch method can effectively provide distributed decisions that achieve better throughput while reducing the number of GBs. Our MAC also allows the CR users to utilize the reserved GBs of primary networks under predefined FCC power constraints. Simulation results indicate that our protocol achieves significant performance improvement compared to previous GB-aware protocols.

Simultaneous assignment of quay cranes and internal trucks in container terminals

This paper studies the assignment of quay cranes to the berthed vessels and the assignment of internal trucks to each quay crane at container terminals. Previous studies have either dealt with the two planning decisions separately or ignored the internal truck capacity constraint when determining the assignments of the quay cranes, thus producing a handling plan of poor overall quality. This paper addresses the assignment of quay cranes and internal trucks simultaneously. A mixed integer programming model is used to assign quay cranes to each vessel and assign internal trucks to each quay crane. The proposed model is validated against an existing model from literature. Numerical experiments with the proposed model using actual container terminal data show that the proposed model reduces the average berthing stay per vessel compared to the existing models in literature in case of limited availability of internal trucks.

Non-iterative eigenstructure assignment technique for finite element model updating

A novel control theory-based eigenstructure assignment (ESA) technique is employed to update the finite element model (FEM) of a linear time-invariant system. The proposed method uses state feedback to produce the gain matrix which in turn updates the existing system matrices through simultaneous assignment of eigenvalue-vector pairs in the FEM generated system matrices. However, unlike general control technique no external input is used to control the system. A subspace identification algorithm is applied to develop the state space model and the eigenstructure of its state matrix is used as the target for the ESA algorithm to update the FEM. Unlike most FEM updating algorithms which use optimization techniques, this method is not iterative (and hence computationally less expensive) as the state matrix gets updated just once yielding the single best possible solution to match the desired eigenstructure. Furthermore, it naturally preserves the basic exploitable properties like symmetry, sparsity, positive definiteness of the updated matrices. The method is first validated numerically on a four-story shear frame subjected to ambient vibrations. Following this, a two-story one-bay aluminium frame is subjected to a suite of excitations in the laboratory, and the response time histories are put through canonical variate analysis algorithm to yield the real system state space model, and hence the modal parameters. Noise is taken care of by singular value decomposition of the signal and performing ensemble averaging of the state matrix in its companion form. A very close conformation of the updated model is observed when compared to the modal parameters extracted from structural response.

Minimization of the Total Traveling Distance and Maximum Distance by Using a Transformed-Based Encoding EDA to Solve the Multiple Traveling Salesmen Problem

Estimation of distribution algorithms (EDAs) have been used to solve numerous hard problems. However, their use with in-group optimization problems has not been discussed extensively in the literature. A well-known in-group optimization problem is the multiple traveling salesmen problem (mTSP), which involves simultaneous assignment and sequencing procedures and are shown in different forms. This paper presents a new algorithm, namedEDAMLA, which is based on self-guided genetic algorithm with a minimum loading assignment (MLA) rule. This strategy uses the transformed-based encoding approach instead of direct encoding. The solution space of the proposed method is onlyn!. We compare the proposed algorithm against the optimal direct encoding technique, the two-part encoding genetic algorithm, and, in experiments on 34 TSP instances drawn from the TSPLIB, find that its solution space isn!n-1m-1. The scale of the experiments exceeded that presented in prior studies. The results show that the proposed algorithm was superior to the two-part encoding genetic algorithm in terms of minimizing the total traveling distance. Notably, the proposed algorithm did not cause a longer traveling distance when the number of salesmen was increased from 3 to 10. The results suggest that EDA researchers should employ the MLA rule instead of direct encoding in their proposed algorithms.

SEK: sparsity exploiting k-mer-based estimation of bacterial community composition.

Estimation of bacterial community composition from a high-throughput sequenced sample is an important task in metagenomics applications. As the sample sequence data typically harbors reads of variable lengths and different levels of biological and technical noise, accurate statistical analysis of such data is challenging. Currently popular estimation methods are typically time-consuming in a desktop computing environment. Using sparsity enforcing methods from the general sparse signal processing field (such as compressed sensing), we derive a solution to the community composition estimation problem by a simultaneous assignment of all sample reads to a pre-processed reference database. A general statistical model based on kernel density estimation techniques is introduced for the assignment task, and the model solution is obtained using convex optimization tools. Further, we design a greedy algorithm solution for a fast solution. Our approach offers a reasonably fast community composition estimation method, which is shown to be more robust to input data variation than a recently introduced related method. A platform-independent Matlab implementation of the method is freely available at http://www.ee.kth.se/ctsoftware; source code that does not require access to Matlab is currently being tested and will be made available later through the above Web site.

Plakilactones G and H from a marine sponge. Stereochemical determination of highly flexible systems by quantitative NMR-derived interproton distances combined with quantum mechanical calculations of (13)C chemical shifts.

In this paper the stereostructural investigation of two new oxygenated polyketides, plakilactones G and H, isolated from the marine sponge Plakinastrella mamillaris collected at Fiji Islands, is reported. The stereostructural studies began on plakilactone H by applying an integrated approach of the NOE-based protocol and quantum mechanical calculations of 13C chemical shifts. In particular, plakilactone H was used as a template to extend the application of NMR-derived interproton distances to a highly flexible molecular system with simultaneous assignment of four non-contiguous stereocenters. Chemical derivatization and quantum mechanical calculations of 13C on plakilactone G along with a plausible biogenetic interconversion between plakilactone G and plakilactone H allowed us to determine the absolute configuration in this two new oxygenated polyketides.

Assigning the set of zeros in control systems with parallel compensation

The problem of ensuring a given set of zeros in a linear multivariable dynamical system with the equal number of inputs and outputs that includes a parallel compensator and feedback loop is considered. Methods reducing this problem to the control of eigenvalues of a certain matrix are proposed; the simultaneous assignment of poles and zeros is reduced to the control of poles of two plants using a single controller. The calculations are based on well-known and well-tested modal control techniques.

Simultaneous Elements of Reality for Incompatible Properties by Exploiting Locality

We show that the extensions of quantum correlations stemming from a "strict" interpretation of the criterion of reality of Einstein, Podolsky and Rosen raise the inadequacy of their ideal experiment for the assignment of simultaneous elements of reality to two incompatible properties. Then, we suggest a different physical situation enabling the simultaneous assignment of objective values of two incompatible observables of a spin particle by means of measurements of two compatible properties of a second correlated spin particle.

A new method for explicit modelling of single failure event within different common cause failure groups

Redundancy and diversity are the main principles of the safety systems in the nuclear industry. Implementation of safety components redundancy has been acknowledged as an effective approach for assuring high levels of system reliability. The existence of redundant components, identical in most of the cases, implicates a probability of their simultaneous failure due to a shared cause—a common cause failure.This paper presents a new method for explicit modelling of single component failure event within multiple common cause failure groups simultaneously. The method is based on a modification of the frequently utilised Beta Factor parametric model. The motivation for development of this method lays in the fact that one of the most widespread softwares for fault tree and event tree modelling as part of the probabilistic safety assessment does not comprise the option for simultaneous assignment of single failure event to multiple common cause failure groups. In that sense, the proposed method can be seen as an advantage of the explicit modelling of common cause failures. A standard standby safety system is selected as a case study for application and study of the proposed methodology. The results and insights implicate improved, more transparent and more comprehensive models within probabilistic safety assessment.

Configurational Analysis of Tetracyclic Dimeric Pyrrole–Imidazole Alkaloids Using a Floating Chirality Approach

The structure elucidation of the palau'amine congener tetrabromostyloguanidine (1), which used interproton distances from ROESY spectra as restraints in a computational approach, the so-called fc-rDG/DDD method, led to a revision of the relative configuration of palau'amine (2) and its congeners in 2007. The recent total synthesis of (±)-palau'amine (2) subsequently confirmed the computed structural revision of the relative configuration. In order to test a broader application range of the fc-rDG/DDD method, the present study investigated two additional dimeric pyrrole-imidazole alkaloids, axinellamine A (3) and 3,7-epi-massadine chloride (4). These calculations allowed the simultaneous assignment of the relative configuration for all eight stereogenic centers of compounds 3 and 4 without using any information from the reported configurations. In contrast to the palau'amine congeners, the fc-rDG/DDD method confirmed the relative configuration originally described for axinellamine A (3) and 3,7-epi-massadine chloride (4).

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