Search

Paramagnetic spectra of \ensuremath{\gamma} and \ensuremath{\alpha}-Ce measured at the same temperature using high-energy neutrons (\ensuremath{\sim}2 eV) yield a 4f occupancy of \ensuremath{\sim}0.8 in \ensuremath{\alpha}-Ce. This phase of Ce also shows single-ion magnetic response but with a high Kondo energy of \ensuremath{\sim}1800 K. In \ensuremath{\gamma}-Ce we observe the $^{2}$${\mathit{F}}_{5/2}$${\ensuremath{\rightarrow}}^{2}$${\mathit{F}}_{7/2}$ spin-orbit (SO) excitation at \ensuremath{\sim}260 meV. Remarkably, \ensuremath{\alpha}-Ce also reveals a broad SO excitation shifted to a higher energy (\ensuremath{\sim}450 meV). These observations reinforce the idea of localized 4f states in \ensuremath{\alpha}-Ce and k-f hybridization as the driving mechanism for the \ensuremath{\gamma}\ensuremath{\leftrightarrows}\ensuremath{\alpha} transition.

Neutron elastic scattering has been used to investigate the magnetic structure of neodymium in the 4- q state below 6K. The magnitudes and directions of the moments associated with each of the four wavevectors present in this phase have been determined, and the results compared to those obtained for the 3- q phase between 6 and 8K.

The low temperature magnetic phases of Nd 1- x Pr x (with x =0.05, 0.10 and 0.15) and Nd 94 Y 06 have been determined by neutron diffraction. The component modulation wave vectors of the 4- q phase are very sensitive to alloying. In Nd 90 Pr 10 , 48 magnetic satellites are observed around a reciprocal lattice point. The number of subharmonic reflections characterising the “archipelago” phase is reduced by alloying.

Neutron inelastic scattering has been used to study the 5f spin dynamics in a polycrystalline sample of UPb3 over the temperature range 2.5–300 K. At all temperatures the Q-averaged response was found to consist of a Lorentzian shaped quasielastic component. No evidence was found for any crystal field excitations below 60 meV. A detailed analysis of the spectra shows a significant Q-dependence of the response in addition to that expected from the free-ion uranium form factor, with an increase in scattered intensity at the (1 1 1) zone boundary.

We have investigated the phase diagram of the dhcp neodymium-lanthanum alloy system through heat capacity and neutron scattering measurements. A change from the incommensurate antiferromagnetic ordering of neodymium to ferromagnetic ordering is reported. This is attributed to changes in electronic bandstructure as a result of alloying.

We have used neutron scattering to investigate the magnetic structure of neodymium between 6 and 8 K. Two phases have been identified in this temperature region, both of which are triple- q . The moments associated with the ordering wavevectors have been determined.

We have investigated by elastic neutron diffraction the antiferromagnetic ordering of a single crystal of neodymium in fields of up to 5 T. A variety of ordered structures have been observed as a function of field and temperature, some of which are not yet understood.

The paramagnetic spectral response of the pseudobinary alloys U(Sn3-xInx), 0 less-than-or-equal-to x less-than-or-equal-to 1.0, have been investigated by neutron inelastic scattering using the time-of-flight technique. The response was found to consist of a single broad quasielastic component varying slowly with temperature. Good agreement was obtained between neutron and bulk susceptibilities at 100 K, whereas at 2.5 K the Q-averaged neutron susceptibility does not show the large heavy-fermion enhancement seen in the bulk measurements.

Research carried out at Loughborough during the last five years on the impedance of Leclanche, alkaline Zn-MnO2, alkaline Zn-HgO, Li-CuO, Li-SO2, Li-SOCl2 primary cells is briefly reviewed. The use of alternating current methods for the estimation of the state of charge of the cells is discussed. A search was made for properties of the impedance of each cell system which change in a marked and reliable manner when a prescribed amount of charge is withdrawn from the cell. It is concluded that simple tests based upon an assessment of these properties are adequate for the estimation of the state of charge of some of the systems studied. However, other systems are not so ‘well-behaved’. The impedance of each cell changed significantly during discharge and, although making measurements of these changes would enable the state of charge to be estimated, the test techniques required would not necessarily be simple. Using the results obtained on the impedance of the cells, test sets have been constructed which provide a digital presentation of the open-circuit voltage and the state of charge of Leclanche cells (Ever Ready type SP11), mercury cells (Mallory, type RM502R) and lithium cells (Mallory, type L032S and SAFT, type LC01). The electronic techniques employed in these test sets are described in outline with reference in block-schematic diagrams. A proposal is made for the construction of a general-purpose tester for primary cells which would incorporate microprocessors and provide an indication of state of charge based upon data relating to impedance, temperature and discharge history. The tester might also be made self-calibrating for field use.

The study of NiCd cells and batteries has led to the requirement for an automated method of removing fixed amounts of charge and logging voltag

This paper describes a portable unit for measuring the charge remaining in nickel—cadmium secondary cells. Exhaustive frequency response tests have confirmed that cell impedance varies very little with charge state, with the possible exception of that at very low frequencies (

The basic principles underlying the selection of a suitable residual capacity test are advanced. Experimental testing techniques, test selection processes and the construction of suitable test equipment are described. An extension of the monitoring of residual capacity to capacity control is proposed.

Summary A case of maxillo-facial injuries in a patient with severe haemophilia is described. Problemsof treatment and management are discussed from both surgical and haematological points of view.

The aim is to design, build and test a practical voiccband HF modem that can cope with frequency selective fading. The main objective is to implement the most cost effective system employing the available serial and parallel signal processor devices that can deal with the appropriate detection algorithms as well as simulate the HF channel itself.

The need for a reliable, and as near as possible fail-safe, multiprocessing system for on-board automatic train operation has resulted in the development of Cyclone I. Time redundancy techniques are used extensively to reduce hardware to a minimum, and to allow no incorrect output conditions arising from transient faults.

The development of a multi-microprocessor system suitable for the automatic control of a railway locomotive is described. The technique of time redundancy is used to reduce the amount of hardware to a minimum and to provide transient fault detection and error correction. The software controlling input/output is separated from the main application programs and is integral with the error checking system software. In this way, the probability of incorrect outputs is considerably reduced when working in an environment likely to cause transient faults. Finally, a duplex Cyclone arrangement is proposed to meet requirements for single-hard-fault tolerance