Microscopic Clustering in Light Nuclei

We review recent experimental and theoretical progress in understanding the microscopic details of clustering in light nuclei. We discuss recent experimental results on $\alpha$-conjugate systems, molecular structures in neutron-rich nuclei, and constraints for ab initio theory. We then examine nuclear clustering in a wide range of theoretical methods, including the resonating group and generator coordinate methods, antisymmetrized molecular dynamics, Tohsaki-Horiuchi-Schuck-R\"opke wave function and container model, no-core shell model methods, continuum quantum Monte Carlo, and lattice effective field theory.Comment: Accepted for publication in Review of Modern Physics, 50 pages, 28 figures, minor change to titl

Stringent upper limit on the direct 3α decay of the Hoyle state in 12C

We investigate an implication of the most recent observation of a second Jπ=2+ state in 12C, which was measured using the 12C(γ,α)8Be(g.s.) reaction. In addition to the dissociation of 12C to an α-particle and 8Be in its ground state, a small fraction of events (2%) were identified as direct decays and decays to excited states in 8Be. This allowed a limit on the direct 3α partial decay width to be determined as Γ3α<32(4) keV. Since this 2+ state is predicted by all theoretical models to be a collective excitation of the Hoyle state, the 3α partial width of the Hoyle state is calculable from the ratio of 3α decay penetrabilities of the Hoyle and 2+ states. This was calculated by using the semiclassical Wenzel-Kramers-Brillouin approach and we deduce a stringent upper limit for the direct decay branching ratio of the Hoyle state of Γ3α Γ <5.7×10−6, over an order of magnitude lower than previously reported. This result places the direct measurement of this rare decay mode beyond current experimental capabilities

Cluster Symmetries and Dynamics

Many light nuclei display behaviour that indicates that rather than behaving as an A-body systems, the protons and neutrons condense into clusters. The α-particle is the most obvious example of such clustering. This contribution examines the role of such α-clustering on the structure, symmetries and dynamics of the nuclei 8Be, 12C and 16O, recent experimental measurements and future perspectives

Optimization of thermochemical heat storage systems by controlling operating parameters and using two reactors

Direct CO2 emissions from space heating and hot water production in buildings has been on a rising trend in recent decades. It is increasingly urgent to develop efficient and low-carbon heating technologies that can reduce energy consumption and shift the load to off-peak times. This work concerns thermochemical heat storage (TCHS), which has the potential to offer flexibility to bridge the energy supply and demand mismatches, and help with load shifting. One of the technical barriers for the use of TCHS is the variation of the outlet conditions for discharge process, which limits the implementation and competitiveness of the technology. Here we propose a new method to overcome the barrier. By using packed-bed based thermochemical reactors packed with silica gel, as an example, we use a Computational Fluid Dynamic (CFD) tool to understand the effectiveness of controlling and optimising the outlet conditions of the TCHS reactor. We demonstrated that, by optimizing the packed bed, a stable outlet temperature could be achieved. Furthermore, the whole TCHS performance could be enhanced, doubling the discharging power and prolonged discharge time by 4 times while keeping the same outlet temperature

Recent applications of the SAMMIE system

Human modelling systems such as SAMMIE can be powerful tools for the design team as they enable predictions to be made concerning problems with clearances, reaching, seeing or the combination of all these requirements that may force unnatural and damaging postures. The potential benefits arising from the use of such systems are discussed below, with reference to some recent projects completed by SAMMIE CAD Ltd

SAMMIE computer aided ergonomics

Human modelling systems can be powerful tools for the design team as they enable predictions to be made of the percentage of future users of the product who may have problems with clearances, reaching, seeing or the combination of all these requirements may force unnatural and damaging postures. When problems are identified, it is possible for all of the design team to scrutinise the data and the assumptions used. The ergonomics problems with a proposed design can be presented visually thereby supporting efficient communication within the design team and solution-orientated action. SAMMIE (System for Aiding Man Machine Interaction Evaluation) is a human modelling computer aided ergonomics design system that was conceived in the late 1960s and by 1978 the system was being used on a daily basis as a consultancy tool. This paper will describe and discuss some of the more important issues that we have had to deal with during the development and application of SAMMIE

The design of supermarket workstations to reduce the incidence of musculo-skeletal discomfort

Statistics provided by the Department of Social Security in Great Britain show that the number of days of certified incapacity because of musculo-skeletal diseases rose from 34.2 million days in 1971/2 to 78.2 million in 1986/7. This alarming rise is costly both to the employee and the employer. This paper describes how one large-supermarket store examined the extent of the problem experienced by their staff and what measures the management took to alleviate the situation. The great majority of studies concerning supermarket workers have examined only the cashiers' workstations (e.g. Wilson and Grey, 1984; Thorne and Russell, 1987, Krueger et al, 1988; Strasser 1990) often because of the introduction of laser scanning systems. The cashiers were typically found to report discomfort in the neck, shoulders, arms and back. A recent study by Ryan (1989) examined supermarket employees in a range of job areas and concluded that the cashiers experienced an excess prevalence of musculo-skeletal symptoms compared to other employees, particularly in the lower back and lower limbs. The discomfort in the lower limbs was associated with standing (whereas the other studies cited examined seated cashiers) and there appeared to be a threshold effect of about 50% of time spent standing for lower limb symptoms to appear. Earlier work by Buckle et al (1986) compared the incidence of musculo-skeletal disorders within female occupational groups including supermarket workers in general. It was pointed out that the supermarket workers showed only slightly lower prevalence rates of back pain than nurses who are known to be a group particularly at risk