Formulation of the addition-shift-sequence problem and its complexity

Selected hetaryl and aryl thioketones react with acetylenecarboxylates under thermal conditions in the presence of LiClO4 or, alternatively, under high-pressure conditions (5 kbar) at room temperature yielding thiopyran derivatives. The hetero-Diels–Alder reaction occurs in a chemo- and regioselective manner. The initially formed [4 + 2] cycloadducts rearrange via a 1,3-hydrogen shift sequence to give the final products. The latter were smoothly oxidized by treatment with mCPBA to the corresponding sulfones.

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Real-Time Hydro-Mechanical Transmission System Simulations for Model-Guided Assessment of Complex Shift Sequence

10.4271/2021-01-0715 ◽

2021 ◽

Author(s):

Yifeng Tang ◽

Jason Rodgers ◽

James McCallum ◽

Yijing Zhang ◽

Yuji Fujii

Keyword(s):

Real Time ◽

Transmission System ◽

Mechanical Transmission ◽

Shift Sequence

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Oxidative cyclization for the synthesis of complex tetrahydrofuran-containing natural products

Pure and Applied Chemistry ◽

10.1351/pac-con-12-10-25 ◽

2013 ◽

Vol 85 (6) ◽

pp. 1175-1184 ◽

Cited By ~ 4

Author(s):

Robert D. C. Pullin ◽

Radosław M. Lipiński ◽

Timothy J. Donohoe

Keyword(s):

Natural Products ◽

Amino Acid ◽

Functional Groups ◽

Lewis Acid ◽

Excitatory Amino Acid ◽

Oxidative Cyclization ◽

Annonaceous Acetogenins ◽

Hydride Shift ◽

Vicinal Diols ◽

Shift Sequence

The osmium-catalyzed oxidative cyclization of vicinal diols onto proximal olefins to generate 2,5-cis-substituted tetrahydrofurans (THFs) has been exploited as the key step for the construction of several complex THF-containing natural products, namely, the annonaceous acetogenins cis-sylvaticin, sylvaticin, and the excitatory amino acid neo-dysiherbaine A. Recently modified conditions that employ a Lewis acid enable the cyclization to proceed under milder conditions, providing greater tolerance to acid-sensitive functional groups, as demonstrated in two of the syntheses. Flexibility for the construction of 2,5-trans-THFs was demonstrated in the synthesis of sylvaticin by utilization of an intramolecular hydride-shift sequence.

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Radar Communication Integrated Waveform Design Based on OFDM and Circular Shift Sequence

Mathematical Problems in Engineering ◽

10.1155/2017/9840172 ◽

2017 ◽

Vol 2017 ◽

pp. 1-10

Author(s):

Cong Li ◽

Weimin Bao ◽

Luping Xu ◽

Hua Zhang ◽

Ziyang Huang

Keyword(s):

Orthogonal Frequency Division Multiplexing ◽

Gray Code ◽

Side Lobe ◽

Waveform Design ◽

Simulation Experiments ◽

Fuzzy Function ◽

Good Ability ◽

Cyclic Sequence ◽

Shift Sequence ◽

Radar Sensing

Based on the orthogonal frequency division multiplexing (OFDM) technique, an intelligent waveform is designed, which is suitable for simultaneously performing data transmission and radar sensing. In view of the inherent high peak-to-mean envelope power ratio (PMERP) and poor peak-to-side-lobe ratio (PSLR) problems in the OFDM based radar and communication (RadCom) waveform design, we propose two technologies to deal with that. To be specific, we adopt Gray code technology to reduce the PMERP and simultaneously choose an optimal cyclic sequence to improve the PSLR of RadCom waveform. In our method, the optimal cyclic sequence is dynamically generated to continuously provide the best waveform according to the change of communication data. In addition, to meet the requirements of different radar detection tasks, two simple methods are utilized to adjust the bandwidth of RadCom waveform. To verify the advantages of the designed waveform, we conduct several simulation experiments to compare with some existing RadCom waveforms. The results show that our designed RadCom waveform can simultaneously achieve lower PMERP and higher PSLR. In addition, our designed RadCom waveform has a thumbtack type fuzzy function and shows the good ability to do multitarget detection.

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Effective encoding strategies for MRI: A two-echo flow/motion and chemical shift sequence with stereo-views

Magnetic Resonance Imaging ◽

10.1016/0730-725x(85)90322-4 ◽

1985 ◽

Vol 3 (2) ◽

pp. 205

Keyword(s):

Chemical Shift ◽

Flow Motion ◽

Shift Sequence ◽

Encoding Strategies

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A decomposition heuristic for rotational workforce scheduling

Journal of Scheduling ◽

10.1007/s10951-020-00659-2 ◽

2020 ◽

Vol 23 (5) ◽

pp. 539-554

Author(s):

Tristan Becker

Keyword(s):

Computational Study ◽

Mathematical Formulation ◽

Workforce Planning ◽

Problem Instance ◽

Workforce Scheduling ◽

Shift Scheduling ◽

Decomposition Approach ◽

Rest Periods ◽

Fixed Set ◽

Shift Sequence

Abstract In rotational workforce planning, a schedule is constructed from a sequence of work and rest periods. Each employee starts at a different part of the schedule, and after a certain amount of time, the schedule repeats. The length of the schedule increases with a higher number of employees. At the same time, various constraints on work sequences and days off have to be considered. For a large number of employees, it is difficult to construct a schedule that meets the requirements. It is important to ensure low solution times independently of the problem instance characteristics. In this work, a novel decomposition approach for rotational shift scheduling is proposed. The decomposition exploits the fact that most constraints in rotational workforce scheduling are imposed on the work shift sequence. By considering a fixed set of blocks to cover the demand, the problem complexity can be greatly reduced. Given a fixed set of blocks, we propose a network model that determines whether a feasible sequence of shift blocks exists. The decomposition approach is applied to the problem structure of the Rotating Workforce Scheduling Problem but may be extended to different problem structures. In a computational study, the decomposition approach is compared to a mathematical formulation and previous exact and heuristic approaches. Computational results show that the decomposition approach greatly outperforms previous heuristics on the standard benchmarks.

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