First observation of a shape isomer and a low-lying strongly-coupled prolate band in neutron-deficient semi-magic 187Pb

Prompt and delayed γ-ray spectroscopy of the neutron-deficient, semi-magic isotope 187Pb has been performed using the recoil-decay and isomer-decay tagging techniques at the Argonne Gas-Filled Analyzer. A new 5.15(15)-μs isomeric state at only 308 keV above the spherical 3/2− ground state is identified and classified as a shape isomer. A strongly-coupled band is observed on top of the isomer, which is nearly identical to the one built on the prolate 7/2−[514] Nilsson state in the isotone 185Hg. Based on this similarity and on the result of the potential-energy surface calculations, the new isomer in 187Pb is proposed to originate from the same configuration. The retarded character of the 308-keV (7/2−)→3/2gs− transition with a deduced B(E2)=5.6(2)×10−4 W.u. can be well explained by the significant difference between the prolate parent and spherical daughter configurations, leading to the shape isomerism. The excitation energy of the isomer is surprisingly low, being roughly half of the excitation energies of the known 0+ intruder bandheads in the neighboring 186,188Pb isotopes. The combined results of the present work and the previous α-decay and laser spectroscopy studies present evidence for triple shape coexistence at low energy in the negative-parity configurations of 187Pb, which is well reproduced by the potential-energy surface calculations

A hybrid approach to locally optimized interpretable partitions of fuzzy neural models

Many learning methods have been proposed for Takagi-Sugeno-Kang fuzzy neural modelling. However, despite achieving good global performance, the local models obtained often exhibit eccentric behaviour which is hard to interpret. The problem here is to find a set of input space partitions and, hence, to identify the corresponding local models which can be easily understood in terms of system behaviour. A new hybrid approach for the construction of a locally optimized, functional-link-based fuzzy neural model is proposed in this paper. Unlike the usual linear polynomial models used for the rule consequent, the functional link artificial neural network (FLANN) is employed here to achieve a nonlinear mapping from the original model input space. Our hybrid learning method employs a modified differential evolution method to give the best fuzzy partitions along with the weighted fast recursive algorithm for the identification of each local FLANN. Results from a motorcycle crash dataset are included to illustrate the interpretability of the resultant model structure and the efficiency of the new learning technique

An Efficient Algorithm for Grid-Based Robotic Path Planning Based on Priority Sorting of Direction Vectors

This paper presents an efficient grid-based robotic path planning algorithm. This method is motivated by the engineering requirement in practical embedded systems where the hardware resource is always limited. The main target of this algorithm is to reduce the searching time and to achieve the minimum number of movements. In order to assess the performance, the classical A* algorithm is also developed as a reference point to verify the effectiveness and determine the performance of the proposed algorithm. The comparison results confirm that the proposed approach considerably shortens the searching time by nearly half and produces smoother paths with less jagged segments than A* algorithm

Effect of different mulch materials on winter wheat production in desalinized soil in Heilonggang region of North China

Freshwater shortage is the main problem in Heilonggang lower-lying plain, while a considerable amount of underground saline water is available. We wanted to find an effective way to use the brackish water in winter wheat production. Surface mulch has significant effect in reducing evaporation and decreasing soil salinity level. This research was aimed at comparing the effect of different mulch materials on winter wheat production. The experiment was conducted during 2002~2003 and 2003~2004. Four treatments were setup: (1) no mulch, (2) mulch with plastic film, (3) mulch with corn straw, (4) mulch with concrete slab between the rows. The result indicated that concrete mulch and straw mulch was effective in conserving soil water compared to plastic film mulch which increased soil temperature. Concrete mulch decreases surface soil salinity better in comparison to other mulches used. Straw mulch conserved more soil water but decreased wheat grain yield probably due to low temperature. Concrete mulch had similar effect with plastic film mulch on promoting winter wheat development and growth

First observation of the decay of the 13/2+ isomer in 183Hg and B(M2) systematics of neutron transitions across the nuclear chart

The decay of the 13/2+ isomeric state in 183Hg was observed for the first time following the α decay of the 13/2+ isomer in 187Pb produced in the 142Nd(50Cr, 2p3n) reaction. Using α−γ delayed coincidence measurements, the half-life of this isomer was measured to be 290(30) μs. This isomer is proposed to deexcite by an unobserved low-energy M2 transition to the known 9/2− member of a strongly prolate-deformed 7/2−[514] band, followed by a 105-keV M1 transition to the bandhead. A lower limit of B(M2) ≥ 0.018 W.u. was deduced for the unobserved transition. The presumed retardation is proposed to be due to the notable shape change between the initial, nearly spherical, and the final, strongly deformed, states. A similar scenario is also considered for the 13/2+ isomer in 181Hg, suggesting both are cases of shape isomers. The B(M2) systematics of neutron transitions across the nuclear chart is discussed