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The paper investigates the effects of emissions constraints and Emissions Trading Scheme (ETS) on the generation scheduling outcome. ETS is a cap-and-trade market mechanism that has been introduced in European Union in order to facilitate CO2 emissions management. This scheme gives generators certain amount of CO2 allowances which they can use to cover emissions produced during energy generation. In a current setting, most of the allowances are given for free. However, under ETS generators also have an opportunity to buy and sell CO2 allowances on the market. Since generation power outputs are bounded by the amount of CO2 emissions that they are allowed to produce over time, it is becoming increasingly important for generating units to manage their allocations in the most profitable way and decide when and how much of permissions to spent to produce electricity. The method proposed here allows for modeling of this new limitation by including costs of buying and selling of CO2 allowance in the generation scheduling procedure. It also introduces additional emissions constraints in the problem formulation. Although CO2 permissions and energy are traded in separate markets, the proposed formulation permits analysis on how emission caps and emission market prices can influence market outcome. The method is illustrated on a 5-unit system. Given examples compare (i) a base-case when all generators have made a decision to use portions of their total free allocations that do not cause any shortfall during the investigated time period; (ii) two cases when the least expensive generators' decisions on the amount of free allowances they are willing to use during the considered period are insufficient. In all cases generators also submit prices at which they expect to be able to 'top-up' or sell allowances on the market, however, only in the second and third case the 'buying' option becomes active and affects generation scheduling and total costs. In addition, the paper investigates how aggregation of emissions allowances of generators belonging to the same company can affect market clearing.

A procedure to estimate the capacity of minihydro plants based on water flow time series forecasting is presented. First, the classic method used for this purpose is introduced and then a set of methodologies to assess the feasibility of minihydro generation and to determine system capacity based on time series forecast is described. The water flow time series is processed to determine the theoretical power generation and to assess if a minihydro plant can be installed. Finally the characteristics of each of the electro-mechanical components for the proposed minihydro plant are selected.

This paper provides an analysis of the “Hydrogen from the Sun” project at the “Ecological House” in northern Italy. The modeling and analysis work is being performed in conjunction with the International Energy Agency Hydrogen Implementing Agreement Annex 18: Integrated Systems Evaluation. A customized library of Matlab/Simulink component models is used to simulate the system and evaluate the hydrogen economics and energy production efficiencies. Two control algorithms are developed for the house using a fuzzy logic and an adaptive control strategy. The economic and steady state effects of these two strategies are compared as are the energy sources used to supply the energy demand of the house. The hydrogen production system consists of an electrolyzer, a photo-voltaic collector, and a battery, linked to both a metal hydride and high pressure gas storage system. The hydrogen supplies a fuel cell, which powers a residential estate. The analysis shows the contribution of the different system components to the overall efficiency and cost of hydrogen. However, the control systems presented also have a significant effect on the hydrogen and electricity cost. Reduction of these costs and an increase in system efficiency require optimal use of the hydrogen stored, as well as the optimized distribution of power supply from the generating components. The analysis shows the initial cost of hydrogen to be 9.36 $/kg, with electricity produced at 0.65 $/kWh using a fuzzy logic control system at an electrical efficiency of 50% (of the full hydrogen house system), based on the lower heating value of hydrogen. The result of using an active control strategy is presented.

Electricity networks are extensive and well established. They form a key part of the infrastructure that supports industrialised society. These networks are moving from a period of stability to a time of potentially major transition, driven by a need for old equipment to be replaced, by government policy commitments to cleaner and renewable sources of electricity generation, and by change in the power industry. This paper looks at moves towards active distribution networks. The novel transmission and distribution systems of the future will challenge today's system designs. They will cope with variable voltages and frequencies, and will offer more flexible, sustainable options. Intelligent power networks will need innovation in several key areas of information technology. Active control of flexible, large-scale electrical power systems is required. Protection and control systems will have to react to faults and unusual transient behaviour and ensure recovery after such events. Real-time network simulation and performance analysis will be needed to provide decision support for system operators, and the inputs to energy and distribution management systems. Advanced sensors and measurement will be used to achieve higher degrees of network automation and better system control, while pervasive communications will allow networks to be reconfigured by intelligent systems.

In this paper we present, for the first time, the hybrid fiber-optic voltage and current sensors interrogated using an arrayed waveguide grating (AWG) device. Due to the excellent dynamic capabilities of an AWG-based interrogator and its improved robustness, the proposed system would be suitable for voltage and current monitoring within an aircraft electrical system. The voltage sensor comprises a multilayer piezoelectric stack, acting as a voltage-to-strain transducer, and a fiber Bragg grating (FBG) used to convert voltage induced strain changes within the stack into wavelength shifts. These wavelength shifts are then analyzed by an AWG. To measure current, the same sensor type is used to monitor a specially designed ferrite-core current transformer. Alternatively, a magnetostrictive transducer is employed instead of piezoelectric stack. It is shown that the system is capable of measuring variable frequency of voltage and current waveforms, typical of those anticipated in the next generation aero-electric power systems. It is also demonstrated that the system can be used for voltage and current harmonic analysis and power quality measurement in such networks.

The Institute for Energy and Environment (IEE) at the University of Strathclyde has developed various fuel cell (FC) systems for stationary and vehicular applications. In particular the author is involved in the development of alkaline fuel cell (AFC) systems. To understand the dynamic behaviour of the system's key element, the alkaline fuel cell stack, a dynamic model was developed allowing the characterisation of the electrochemical parameters. The model is used to forecast the behaviour of the fuel cell stack under various dynamic operating conditions. The so-called Nernst potential, which describes the open circuit voltage of the stack, is calculated using thermodynamic theory. Electrochemistry theory has been used to model the sources of the electric losses within the FC, such as activation, ohmic and concentration losses. The achievable value of this paper is the first publication of a detailed dynamic AFC based on mass balance, thermodynamics and electrochemical theory. The effects of the load changes on various fuel cell parameters, such as electrolyte concentration and concentrations of dissolved hydrogen and oxygen were covered in this investigation using the author's model. The model allows a detailed understanding of the dynamic effects within the AFC during load change events, which lead to the experienced electric response of the overall FC stack.

This paper presents the design details of a biogas gas plant and fuel cell installation that will provide a practical solution on an island (and be applicable in other remote and rural areas) where connection to the grid can be expensive, and where biofuels can be produced on site at no significant extra cost. In situ use of biomass and organic waste streams have the potential to provide the key to energy recovery and sustainability from biodegradable waste. The scheme described in this paper meets the new EU regulations covering (i) the landfill directive, (ii) the animal by-products regulations, and (iii) the biowaste directive. Traditionally biogas fuels have been used in combustion engines for electric power generation. However, there are now clear indications that given the current developments in reformer technologies, hydrogen gas can be produced from methane-derived anaerobic digestion of organic waste material-much of which is currently land filled. Hence, when utilized in fuel cells this offers the prospect of achieving higher generating efficiencies, and additionally, important environmental benefits will be achieved through mitigating greenhouse gas emissions. The solid waste from the process provides a valuable organic fertiliser which can be returned to the land thereby displacing chemical fertilisers currently in wide spread use.

This paper presents a review of existing dynamic electrical battery models and subsequently describes a new mathematical model of a lead acid battery, using a non-linear function for the maximum available energy related to the battery discharge rate. The battery state of charge (SOC) is expressed in a look-up table relative to the battery open circuit voltage (VOC). This look-up table has been developed through low discharge experiments of the battery modelled. Further, both the internal resistance and self-discharge resistance of the battery are subsequently expressed as functions of the open circuit voltage. By using an electrical model with these characteristics and a temperature compensation element to model different rates of charge and discharge, a relatively simple and accurate battery model has been developed. The new model takes into account battery storage capacity, internal resistance, self-discharge resistance, the electric losses and the temperature dependence of a lead acid battery. It is shown in this paper how the necessary parameters for the model were found. The battery modelled was a Hawker Genesis 42 Ah rated gelled lead acid battery. The simulation results of the new model are compared with test data recorded from battery discharge tests, which validate the accuracy of the new model.

It is now becoming increasingly clear that the in situ use of biomass and organic waste streams are likely to provide the key to energy self sustainability for islands and remote communities. Traditionally biofuels have been used in combustion engines for electric power generation, however, when replaced by fuel cells there is the prospect of achieving higher generating efficiencies, coupled with, in some instances, the opportunity to produce biofuel at a cheaper rate than conventional fuels. Additionally, important environmental benefits can be achieved by way of mitigating greenhouse gas emissions, whilst providing a carbon sink. This paper presents the design details of such an installation that will provide a practical solution on an island (and be applicable in other remote and rural areas) where connection to the grid can be expensive, and where biofuels can be produced on site at no significant extra cost.

This paper summarises the energy policies that the UK Government has enacted in order to achieve its renewable targets by 2010. Current policies are designed primarily to support large-scale renewable projects through Renewable Obligation Certificates, Levy Exemption Certificates and capital grant schemes. Non-profit domestic and non-profit community renewable projects are also eligible for grant support. First-hand experience of privately owned renewable projects indicate that existing renewable policy is insufficient in its support of both small-scale and community-based profit oriented renewable energy (RE) schemes. Primary and secondary survey information suggests that people living in regions where RE will be situated may generally be inclined to support broader uses of renewables in these regions. Small-scale renewables can make a significant cumulative contribution to the RE mix. The results reported in this paper support the contention that the Government could go further towards approaching its targets through rural-focused changes to its energy incentive programmes.

In safety critical components, the capability of an inspection may need to be demonstrated by an independent process of inspection qualification (IQ). Due to the skill level of the manpower involved, IQ is both costly and time consuming. Therefore, an approach that can aid the production of the required documentation would be beneficial. This paper presents a practical example in the form of a case study, which demonstrates how an intelligent approach to IQ, utilising smart software operating within the context of a non-destructive testing Workbench, can be used to evaluate the capability of an ultrasonic inspection. This is accomplished using four interactive software tools which include: a beam-coverage analyser, a worst-case defect search engine, a flaw modelling expert system and a case-based reasoning system to retrieve previously measured data. This paper discusses the motivation for such an approach and the benefits it provides.

This paper presents a dynamic model of a protection system based on a differential feeder protection along with the primary power system. A commercially available relay is modelled and its functions explained. A general primary power system model structure that includes a fully integrated protection system model is discussed. The protection system model contains dynamic models of both the relays and the transducers. A technique will be described for developing an accurate dynamic model of a numerical protection relay using actual microprocessor codes from a commercially available relay. Finally, the practical application of the analysis under abnormal system conditions is demonstrated. Different faults are applied to the internal and the external regions of the feeder, and the response of the relays examined.

The design process of a SOFC plant dynamic model for a power systems simulation (PSS) commercial software package has revealed the trade-off between the satisfaction of the network dynamic requirements and a safe and durable cell operation that the plant controller should implement. This paper describes the initial fuel cell stack and power conditioner modelling methodologies that have addressed such issues.

In this paper we consider the problem of generator maintenance scheduling (GMS) in power systems. A genetic algorithm with a fuzzy evaluation function is proposed in order to overcome some of the limitations of conventional modelling and solution methods. A test GMS problem is formulated with a reliability objective and flexible and crisp constraints. A rule base and fuzzy sets are formulated for the objective and the flexible constraint using experience of solutions to the problem, and used to define a fuzzy evaluation function. This is used in a genetic algorithm (GA) with an integer representation of the schedule to solve the test problem. The results obtained from the GA with the fuzzy evaluation function are compared with those obtained using crisp evaluation functions. The comparison shows that the GA with the fuzzy evaluation function is an effective and practical approach for finding good solutions for GMS with flexible constraints.

Condition monitoring of electrical plant represents an area of great interest to both manufacturing and utility companies within the electricity supply industry. De-regulation and privatisation entail that utilities must operate their systems in an optimal fashion and one of the technologies which can facilitate this is condition monitoring. Condition monitoring has a number of important benefits: unexpected failures can be avoided through the possession of quality information relating to the on-line condition of the plant and the consequent ability to identify faults or problems while still in the incipient phases of development; maintenance programmes can be condition based rather than periodically based; the plant may be utilised more optimally through the use of information relating to the plant's real-time condition and/or performance – for example, the plant may be driven temporarily beyond its stated capacity if it is known that this will not cause any short-term problems. This paper will cover the generic capabilities of artificial neural networks, in both estimation and classification mode, for condition monitoring applications, using examples based around work that the authors have carried out with respect to the monitoring of a power transformer.

This paper presents the background to the ongoing research and development work into optical current measurement devices at Strathclyde University. Details of a new reflective sensor geometry and potted epoxy housing are given, and problems associated with the epoxy curing are noted. A temperature compensation system for the current sensor is described and results showing an accuracy improvement from ≈31% to 1.4% are given.

A rapid cold hardening process is reported in first instar larvae of Frankliniella occidentalis. When larvae are transferred directly from 20 degrees C to -11.5 degrees C for 2h there is 78% mortality, whereas exposure to 0 degrees C for 4h prior to transfer to -11.5 degrees C reduces mortality to 10%. The response can also be induced by exposure to 5 degrees C for 4h or by gradual cooling at rates between 0.1 and 0.5 degrees C min(-1.) The acquired cold tolerance is transient and is rapidly lost (after 1h at 20 degrees C). Rapid cold hardening extends survival times at -11.5 degrees C and depresses lethal temperatures in short (2h) exposures. Rearing at 15 degrees C (12L:12D), (a cold acclimation regime for F. occidentalis), does not protect against the cold shock induced by direct transfer to -11.5 degrees C (which rapid cold hardening does) but does extend survival time at -5 degrees C (i.e. increased chill tolerance) whilst rapid cold hardening does not. The rapid and longer term cold hardening responses in F. occidentalis therefore appear to have different underlying mechanisms.

The paper reports the results of low pressure experiments designed to validate the mechanism and comparison of model results with experiment

With the privatization of the electric power industry in the UK, great interest is being shown in the likely relationship between suppliers and consumers in the new market scenario far energy sale and purchase. In an effort to improve utility economies, it is expected that greater use will be made of load management techniques, both direct and indirect. The use of dynamic or spot-prices offers the means which is most consistent with market economics while still providing the utility with a load management alternative whenever necessary.

Novel tariff structures have been introduced by power utilities over the past two decades in order to induce load shifts to achieve the aims of load management strategies. As a result of the availability of reliable communications between suppliers and consumers, new ‘smart’ metering equipment and the re-organization of the UK power supply industry, the potential for dynamic- or spot-price based tariffs has been recognized. In order to ensure the successful introduction of such a pricing scheme, it is important to make use of accurate consumer process models as well as spot-price behavioural models to provide the means by which a consumer would optimize his production schedules in the light of rapidly changing tariffs. This paper builds up consumer models from fundamental process characteristics and applies optimizing techniques incorporating spot-price models in order to develop algorithms which would minimize production costs and contribute towards the philosophy of joint supplier/consumer optimality through spot-pricing.

This paper presents a method for setting electricity tariffs for use within a distribution power utility. The paper considers a way of reducing the peak demand by using price as a signal to communicate messages to consumers. There have been many studies on electricity pricing and all have drawn the general conclusion that the price of electricity is a significant factor which can be used in load management schemes. This view leads to the need to investigate quantitatively the responsiveness of demand to the price of electricity or, in other words, the price elasticity of the demand. The paper develops an econometric model for the demand for electricity in the domestic sector. The elasticity value obtained is then incorporated into novel time-of-day tariffs which embody factors for inclusion in a load management strategy. Two methods of setting electricity tariffs are presented in this paper. First, the Linear Programming method (LP): a time-of-day tariff is formulated by using a Linear Programming method. In this method, a typical electrical load profiles for each type of load (e.g. domestic, commercial and industrial) is used along with the consumer class and targeted revenue for the particular class. Second, the Total Surplus (TS) method. In this method the tariff is set by maximizing the total joint surplus of consumers and producers in the electrical energy sector. The economic basis of this method is to set the price equal to the marginal cost of the product, namely electrical energy. However, in practice this may not achieve the required aims and one has to seek a ‘second best’ solution in which price is derived by incorporating the load factors and elasticities into the cost elements. This combination allows a utility to adjust the price of electricity to meet required revenue targets and to satisfy the demand for electrical energy.

ISSUE: Duke University Medical Center is an 800-bed university-affiliated medical center. An evaluation of annual MRSA data identified 4 areas (3 ICUs, one inpatient unit) where MRSA rates had increased dramatically in the first 6 months of 2004. Infection Control (IC) developed a program aimed at reducing the rate of nosocomial MRSA by promoting involvement of the clinical service unit (CSU) in identifying infection prevention strategies. PROJECT: In June 2004, IC began the Duke MRSA Initiative, for targeted areas with significant MRSA rate increase over the past 6 months. Infection Control then met with key leaders within the CSU. Data on unit-specific trends were presented and members were educated on the risk and implications of patients acquiring MRSA. Upon completion of the presentation each CSU identified methods to decrease their MRSA rate, with input from IC. This initiative was first done in the Neuroscience CSU. The interventions included inservices for all staff, initiation of a hand hygiene “time out,” initiation of an admission screening protocol and increased diligence in environmental cleaning. This initiative was also followed in the Musculo-Skeletal CSU, Surgical CSU and the Medicine CSU. Different interventions were formulated for each CSU, because they were able to identify specific areas in need of change. The role of IC was advisory, with guidance provided with inservices, skills day education and Physician's Grand Rounds. RESULTS: With the Duke MRSA Initiative in place, all 4 units targeted for MRSA reduction were successful in decreasing their rates from July-December 2004. The Neuroscience CSU rate decreased from 4.9/1000 pt. days to 0.93, the Musculo-Skeletal CSU rate from 4.0/1000 pt. days to 0.38, the Surgical CSU rate from 3.3/1000 pt. days to 0.78 and the Medicine CSU rate from 3.0/1000 pt. days to 1.1. IC continued to monitor MRSA rates and to ensure that the interventions were still in place. 2005 MRSA data show a sustained nosocomial infection reduction among the units: Neuroscience CSU at 2.4, Musculo-Skeletal CSU at 0.42, Surgical CSU at 2.0, and Medicine CSU at 1.3. LESSONS LEARNED: With increasing nosocomial and community-acquired MRSA rates, IC teams must use innovative methods to reduce and sustain low nosocomial MRSA rates. When the unit takes ownership to reduce their rate of MRSA, there is an increase in unit participation with a notable decrease in MRSA rate.

ISSUE: Missouri Baptist Medical Center is a 499-bed community hospital with two 10-bed, medical-surgical intensive care units (ICUs). The 2001 ventilator-associated pneumonia (VAP) mean rate for both ICUs was 9.54/1,000 ventilator days. A VAP prevention team was formed with Infection Control, critical care (CC) medical director, nurse managers and educators, respiratory therapy (RT) managers, and a pharmacist, dietician, and pulmonologist. PROJECT: Analysis of actual versus recommended care of ventilated patients identified areas for improvement. Assessment of 2001 VAP data, 70% of patients developed VAP 2–7 days after intubation. Our ventilator discontinuation protocol (VDP) was revised. RT and the CC nurse assessed patient tolerance for spontaneous breathing using set criteria. If a wean was tolerated, an extubation order was obtained. WHAP VAP (Wean Patient, Hand Hygiene, Aspiration Precautions, Prevent Contamination) education was used in posters and a self-study module. CC physicians, staff, and RT completed the module. Staff received education on elevating the head of bed (HOB), VAP risk factors, and prevention strategies. VAP rates were shared and posters were placed in ICUs, RT, and physical therapy. An intubated doll with HOB elevated 30 degrees was placed in a chair next to the educational poster. RESULTS: In 2001, pre-intervention HOB data was collected (n=154): patients HOB elevated >30 degrees = 72 (46%); patients able to tolerate HOB elevation >30 degrees but not elevated = 62 (40%). One-month post-intervention HOB data (n=197): patients HOB elevated >30 degrees, 113(57%)—a 27% increase after education; patients able to tolerate the HOB >30 degrees but not elevated = 69 (35%)—a 14% decrease. Our VAP mean rate decreased from 9.54 to 4.15/1,000 ventilator days. LESSONS LEARNED: The VDP improved communication between CC and RT. Staff compliance with hand hygiene continues to be a challenge. Staff were taught to correctly read the HOB level, which had often been misread. When a multidisciplinary team dedicates resources and education for VAP prevention, infection rates can be reduced.

Temperature dependence measurements of the rates of reaction of C 2 (X 1 Σ g + ) with H 2 and CH 4 are reported along with similar measurements for an equilibrated mixture of C 2 (X 1 Σ g + and a 3 Π u spin states with O 2 over the 300–600 K range. All the reactions are characterized by low activation energies. Singlet C 2 likely reacts with hydrocarbons by an insertion mechanism followed by fragmentation.

C3 disappearance rate constants at room temperature are reported for reactions with alkenes, alkynes, and allenes. C3 radicals are generated by multiphoton UV excimer laser photolysis of benzene and monitored using laser induced fluorescence. Possible reaction mechanisms are discussed.

The CH3O( X 2E) radical produced by the 266 nm photolysis of CH3ONO is characterized by laser-induced fluorescence. Using a flowing gas cell the reaction rate of CH3O( X 2E) with NO is measured to be (2.08 ± 0.12) × 10−11 cm3 s−1 molecule−1 based upon disappearance of CH3O and appearance of HNO detected by laser induced fluorescence. Upper limits for CH3O reactions with CH4, CO, N2O, NH3, CH3OH, (CH3)3CH and CH2CHCH2CH3 are reported. These reactions are all too slow to measure under our experimental conditions.

The gas-phase reactions of NH(a 1 Δ) with H 2 and selected saturated and unsaturated hydrocarbons have been studied over the 250-600 K temperature range. Olefin reactions proceed at near the gas kinetic collision rate and show no temperature dependence. H 2 and saturated hydrocarbons show temperature-dependent reactions rates, with activation energies of = 0.8-2 kcai/mole. No evidence of electronic quenching of NH(a 1 Δ) to the ground state was observed with any of the hydrocarbons studied. First-order reactions rates, Arrhenius A factors and activation energies for the reactions are reported. We discuss a mechanistic interpretation of the kinetics in view of earlier kinetic and reaction-product studies and ab initio SCF Cl calculations.

In the preceding paper it was shown that the 266 nm photodissociation of HN3 gives rise to NH fragments exclusively in the vibrationless a(1Δ) state with about 900 cm−1 of rotational energy. These fragments collisionally react with HN3 to produce NH2(2A1) in a chemiluminescent reaction. The time resolved chemiluminescence emission is used to determine the reaction rate for NH(1Δ) + HN3 → NH2(2A1) + N3(2Πg). The reaction rates of NH(1Δ) with several other species, HCl, CH4, C2H4, C3H6 and C6H12 are reported. Possible mechanisms for these reactions are considered. Condensed phase experiments are reported describing the addition reaction of NH(1Δ) with cyclohexane.

The fluorescence emission spectrum and analysis of NSF vapor is presented. Single vibronic level excitation near the S 1 origin gives rise to a 10 μs radiative decay. The fluorescence lifetime for excitation of levels with ≳ 4500 cm −1 excess vibrational energy becomes controlled by a unimolecular radiationless process which is likely photodissociation; the dependence of this radiationless rate on energy and vibrational mode is investigated. The perturbations resulting from coupling of zero-order S 1 states with other vibronic levels which control the excited state dynamics of SO 2 are apparently not operative for NSF. Attempts are made to rationalize the grossly different dynamic behavior of the S 1 levels of these two otherwise very similar systems.

Theories of particle charging based on macroscopic boundary value solutions to the diffusional equation are not applicable to many practical cases where the ion density is less than two orders of magnitude greater than the particle concentration. A new charging equation based on kinetic theory is presented which evaluates the charging rate in terms of the probability of collisions between the dust particles and ions. In order to simplify the mathematics, the surface of the particle is considered as being divided into three charging regions and separate charging rates are calculated for each region. The total charging rate is the sum of these three individual rates. For large particles and high electric fields this theory predicts essentially the same charging rate as the classical field charging equations of Rohmann (1923) and Pauthenier (1932). For low electric fields the theory reduces to White's (1951) diffusional charging equation. Agreement is within 25% of Hewitt's (1957) experimental results over the entire range of variables where data are available. For practical charging times in electrostatic precipitators the agreement is within 15%.

Single and multiple photon processes are identified in the 193 nm excimer laser photolysis of CS2. CS(X1Σ+, υ = 1 to 5, J = 5 to 45) is observed by dye laser induced fluorescence of the A1Π ↔ ; X1Σ+ transition, following the single photon 193 nm photolysis of CS2. Multiple photon 193 nm generation of CS fragment emission from 620 to 170 nm is also reported. A partial assignment of the emission spectrum identifies fluorescence from the CS A′1Σ+ and A1Π states.

The lowest energy metastable electronic states of the nitric oxide and molecular oxygen cations have been studied using Fourier transform mass spectrometry. Using very low neutral reactant pressures and ion trapping periods of up to several seconds, the radiative relaxation rate of the metastable ion becomes competitive with its reaction rate. In this fashion both kinetic information and the radiative lifetime of the metastable state are obtained. The measured rate constants for the reactions of NO+ (a3Σ+) with CO2 [k = (1.0 ± 0.2)×10−9 cm3/s] and of O2+ (a4Πu) with Ar [k = (4.9 ± 1.5)×10−10 cm3/s] are in agreement with earlier results. The measured lifetimes of the NO+ metastable (τ = 1.45 s) and the O2+ metastable (τ = 0.22 s) are discussed using a four-state spin-orbit coupling model which predicts metastable radiative lifetimes which agree reasonably well with the experimental values.

A new semi-empirical, approximate theory for predicting electrical conditions is described. In the approximate theory, analytical expressions are derived for calculating voltage-current characteristics and electric potential, electric field, and space charge density distributions. Comparisons of numerical and approximate solutions over a wide range of possible precipitator geometries and electrical operating points indicates that for practical purposes the approximate theory can be used in lieu of the more rigorous numerical theory. This saves large amounts of computer time and makes possible hand calculator usage. Recent in situ gaseous ion mobility data which are needed in the models are presented. For coal fired power plants, the reduced effective ion mobility in positive corona is found to be 1.6 times that for negative corona. Approaches for describing particulate space charge effects in the gas and electrical conditions in the collected particulate layer are briefly discussed.

The ν 5 rotation-vibration fundamental band and the ν 5 + ν 9 band of diacetylene in the region 2000–2037 cm −1 have been measured to an accuracy of better than ±0.004 cm −1 using a tunable-diode laser spectrometer. The l -type doubling in the ( ν 5 + ν 9 − ν 9 band has been resolved. Line positions, assignments, band origins, and rotational constants B ′ v , B ″ v , D ′ v , and D ″ v are reported.

A photofragment spectrometer has been designed to directly probe by laser induced fluorescence the internal energy distributions of fragments resulting from unimolecular decomposition. Results for photodissociation of ICN at 266 nm show that CN radicals are formed primarily in the 2Σ+ ground electronic state population distributions: Nν″=1/Nν″=0 = 0.012, Nν″=2/Nν″=0 = 6 × 10−4. Nν″=3/ Nν″=0 3000 K. Less than 0.1% of the CN radicals are formed initially in the A 2Π electronically excited state.

Acetylene is photolyzed with a high power ArF pulsed excimer laser at 193 nm. Weak CH(A2Δ→X2Π) emission at 431.8 nm is shown to result from two-photon absorption by C2H2, while strong C2(A1Π→1Σg+) Phillips band emission between 690 and 1100 nm likely results from secondary absorption by the C2H fragment. Weak C2(d3Πg→a3Πu) Swan band emission between 440 and 560 nm originates from a three-photon process. In addition, the C2(C1Πg→A1Πu) Deslandres-d'Azambuja system is identified as weak emission bands in the near UV, overlapping an apparent continuum which extends throughout the visible. Radiative lifetimes of 119 ±6 ns and 10.1 ± 1.2 μs are measured for the C2d3Πg(υ′= 0), and A1Πu(υ′ = 4) states, respectively. The present results indicate that it is possible to generate large yields of high energy fragments with pulsed excimer lasers, opening up an energy region which was only previously accessible with far-vacuum-UV photolysis sources. Such fragments can be spectroscopically characterized, or can be used as reactants in kinetic studies.

C3 reaction rates with ethene, acetylene and various of their alkyl-substituted derivatives are measured in the temperature range 295–610 K. Reactions with ethene and acetylene have 6–8 kcal/mol activation energies which become negative for the multiply alkyl-substituted species. The reaction chemistry of C3 is compared with similar species and we conclude that the mechanism involves electrophilic addition at the carbon-carbon multiple bond. Reaction rates are apparently pressure independent over the range of 5–100 Torr.

A fluorescence excitation spectrum of (CH 3 ) 2 CHO (isopropoxy radical) is reported following photolysis of isopropyl nitrite at 355 nm. Rate constants for the reaction of isopropoxy with NO, NO 2 , and O 2 have been measured as a function of pressure (1–50 Torr) and temperature (25–110°C) by monitoring isopropoxy radical concentrations using laser-induced fluorescence. We have obtained the following Arrhenius expressions for the reaction of isopropoxy with NO and O 2 respectively: (1.22±0.28)×10 −11 exp[(+0.62±0.14 kcal)/ RT ]cm 2 /s and (1.51±0.70)×10 −14 exp[(−0.39±0.28)kcal/ RT ]cm 3 /s where the uncertainties represent 2σ. The results with NO 2 are more complex, but indicate that reaction with NO 2 proceeds more rapidly than with NO contrary to previous reports. The pressure dependence of the thermal decomposition of the isopropoxy radical was studied at 104 and 133°C over a 300 Torr range using nitrogen as a buffer gas. The reaction is in the fall-off region over the entire range. Upper limits for the reaction of isopropoxy with acetaldehyde, isobutane, ethylene, and trimethyl ethylene are reported. We have performed the first LIF study of the isopropoxy radical. Arrhenius parameters were measured for the reaction of i -PrO with O 2 , NO, NO 2 , using direct radical measurement techniques. All reactions are in their high-pressure limits at a few Torr of pressure. The rate constant for the reactions of i -PrO with NO and NO 2 reactions exhibit a small negative activation energy. Studies of the i -PrO + NO 2 reaction produce data which indicate that O( 3 P) reacts rapidly with i -PrO. Unimolecular decomposition studies of i -PrO indicate that the reaction is in the fall-off region between 1 and 300 Torr of N 2 and the high-pressure limit is above 1 atmosphere of N 2 .

A tunable dye laser has been used to excite single vibronic features in the low-pressure vapor of CrO 2 Cl 2 . The fluorescence spectrum, fluorescence excitation spectrum and time-resolved fluorescence decay are discussed. It is shown that the active ν′ 4 and ν″ 4 modes are the same frequency in the gas phase, thus collapsing the sequence congestion normally observed in gas-phase spectra. This degeneracy makes impossible the excitation of single vibronic levels. It is shown that the fluorescence lifetime of the excited state in all except the vibrationally cold level is severely shortened by unimolecular radiationless decay. This radiationless rate is strongly dependent upon the partitioning of energy into various excited-state modes. The radiative lifetime of the vibrationally cold excited state is (1.34 ± 0.08) μs and the apparent bimolecular quenching rate is (5.9 ± 0.2) × 10 −10 cm 3 /molecules. No evidence of emission from the lowest-energy excited electronic state recently reported by Spoliti [J. Mol. Spectrosc. 52 (1973) 146] is observed.

Ammonia is photolyzed with an ArF excimer laser at 193 nm. NH 2 is formed in the A 2 A 1 state, detected through the identification of A 2 A 1 → X 2 B 1 emission bands between 620 and 1100 nm, and also in the X 2 B 1 state, identified by dye laser induced fluorescence on the A ← X transition. The A-state yield is about 2.5% relative to the X-state. The A 2 A 1 state has a propensity for being formed in high K a rotational levels v 2 vibrational levels of the A 2 A 1 state appear to be populated in a monotonically decreasing distribution, with an average vibrational energy content of 1000 cm −1 . Rotational populations are deduced for the 050 Σ vibrational level of the A 2 A 1 state. The colder-than-room-temperature rotational distribution ( T TDI = 210 ± 40 K) is explained by angular momentum conservation arguments. The vibrational and rotational features observed in the dye laser induced fluorescence excitation spectrum of NH 2 A←X could not be assigned at near collision-free pressures. However, under thermalized conditions, the 090 ← 000 Σ, 090 ← 000 Δ, 0 100 - 000 π and 0 100 ← 000 φ bands are clearly identified. Arguments are presented which show that the nascent X 2 B 1 photofragment is created either with the v 2 vibrational population, or the K a rotational population inverted. NH A 3 Π → X 3 Σ − and b 1 Σ + → X 3 Σ − emission are also detected at 336 and 471 nm, respectively. Formation of NH A 3 Π and b 1 Σ + si attributed to two-photon resonance processes

C 2 (X 1 Σ + g ) disappearance rate constants at 298 K have been determined for reactions with H 2 : (1.38±0.06) × 10 −12 cm 3 s −1 molecule −1 ; CH 4 (1.87±0.05) × 10 −11 cm 3 s −1 molecule −1 ; C 2 H 6 : (1.59±0.05) × 10 −10 cm 3 s −1 molecule −1 : C 2 H 4 : (3.26±0.05) × 10 −10 cm 3 s −1 molecule −1 : C 2 F 4 : (5.99±0.14) × 10 −11 cm 3 s −1 molecule −1 : O 2 : (2.82±0.09) × 10 −12 cm 3 s −1 molecule −1 : and CO 2 : no apparent reaction. The C 2 (X 1 Σ − g ) was produced by multiphoton UV excimer laser photodissociation of hexafluorobutyne-2. These results are compared to the reaction rates of C 2 (a 3 Π u ). The rates for O 2 reactions are the same for both C 2 states and no reaction is observed for CO 2 with either C 2 state. However, C 2 (X 1 Σ − g ) reacts considerable faster than C 2 (a 3 Π g ) with hydrogen and hydrocarbons. The presence of an allowed hydrogen atom exchange reaction for ground state C 2 to form ground state C 2 H which is forbidden for metastable triplet C 2 is postulated to account for the disparities in reaction rates. Electronic orbital correlation effects are proposed as an explanation.

Ten thousand patients presenting for anaesthesia in the British Isles were questioned about a possible history of atopic or allergic disorders. The overall percentage frequency of atopy was 8.5, comprising eczema 2.4, hay fever 3.8 and asthma 3.5. The frequency of allergies was 13.5, of which penicillin was the most common (6.2). Females had a significantly greater frequency of atopy or allergy than males. Patients with a history of atopic disorders had a higher frequency of allergies than the non-atopic group (36.2% compared with 11.4%) and vice versa.

Laser induced fluorescence of C2O is observed following the 266 nm laser photodissociation Of C3O2. Excitation spectra of C2O(A3Πi↔-~X3Σ− are consistent with previous absorption studies of C2O. A number of new transitions are identified and assigned. Fluorescence spectra have been recorded following single vibrational level laser excitation. Bands are assigned to ground state vibrational progressions. Values of 1967 and 1063 cm−1 are found for υ1″ and υ3″ stretching vibrations in the X3Σ − state. A subband structure in the fluorescence spectrum is observed and discussed.

Detailed analyses of the electronic, vibrational, and rotational distributions of NH formed by photolysis of HN3 at 266 nm are given. NH is formed primarily in the a (1Δ, ν = 0) state with ≈900 cm−1 state with ≈900 cm−1 rotational energy and ⪅ 5000 cm− of translational energy. In addition, a new chemiluminescent reaction is reported: NH(1Δ) + NH3 → NH2(2A1) + N3. The rate constant for this reaction is in agreement with an earlier measurement of the disappearance of NH(1Δ) by an absorption technique.

Of 131 patients with mild concussion, 19 (14.5%) still had symptoms after 1 year. Of these 19 patients, 10 had some symptoms of which they had not complained at 6 weeks. Symptoms at 1 year were more common among women and among patients who had had positive neurological findings at 24 h. Of the 19 patients who had symptoms at 1 year, 8 were involved in law suits and 6 had been suspected of malingering 6 weeks after their accident. Five of these patients were both involved in law suits and suspected of malingering.

C 2 a 3 Π u is produced by multiphoton UV excimer laser photodissociation of hexafluorobutyne-2 or benzene. The rate of C 2 depletion is monitored using laser induced fluorescence. The disappearance rates of C 2 a 3 Π u are reported over the temperature range of 300–600 K for reactions with H 2 , D 2 , C 2 H 6 , C 3 H 8 , n -C 4 H 10 , and C 2 H 4 and intersystem crossing due to collisions with Xe. The rates are (1σ confidence limits): Reactant k ( T ) cm 3 molecule −1 s −1 H 2 (1.55 ± 0.10) × 10 −11 exp [(−3012 ± 31)/ T ] D 2 (1.80 ± 0.22) × 10 −11 exp [(−3710 ± 72)/ T ] C 2 H 6 (2.42 ± 0.10) × 10 −11 exp [(−919 ± 15)/ T ] C 3 H 8 (1.84 ± 17) × 10 −11 exp [(−97 ± 36)/ T ] n -C 4 H 10 (4.9 ± 0.5) × 10 −11 exp [(−71 ±41)/ T ] C 2 H 4 (1.20 ± 16) × 10 −10 exp [(5 ± 46)/ T ] Xe (5.54 ± 0.14) × 10 −12 exp [(24 +- 30)/ T ] Probable mechanisms for these reactions are discussed.

An analysis of the primary photodissociation products resulting from the 193 nm photolysis of HNCO is reported. The major fragments are NH(a 1 Δ, υ′ = 0) and CO(X 1 Σ + ). Reaction of NH(a 1 Δ) with O 2 and with HNCO produces only non-emissive products, A rapid E-E, V energy transfer occurs for collisions with O 2 . The time-resolved fluorescence rise of NH(X 3 Σ − , υ′' = 0) resulting from NH(a 1 Δ) collisions with O 2 yields an energy transfer rate constant of 1.55 × 10 −11 cm 3 molecule −1 s −1 .

Radiative lifetimes and quenching rate constants have been measured for the A 2 A 1 state of NH 2 , formed through ArF excimer laser photolysis of NH 3 at 193 nm. The NH 2 (A 2 A 1 → X 2 B 1 ) emission is discrete, allowing single vibrational and rotational levels to be isolated. An average radiative lifetime of 31 ± 4 μs and an NH 3 quenching rate constant of (6.1 ± 0.2) × 10 −10 cm 3 molecule −1 s −1 is found to be independent of the K ″ a rotational level and ν′ 2 vibrational level for K ″ a = 1, 4, 5 and 6 and ν′ 2 = 6, 7 and 8. The 050 Σ level ( K ′ a = 0) lifetime is slightly longer (46 ± 6 μs) and its quenching rate constant somewhat lower [(5.0 ± 0.2) × 10 −10 cm 3 molecule −1 s −1 ]. These lifetimes are interpreted as radiative lifetimes of levels of the A 2 A 1 state, unperturbed by Renner—Teller coupling with the ground state. The quenching by NH 3 is shown to be predominantely electronic quenching of the A 2 A 1 state, with vibrational and rotational relaxation within the excited state being at least ten times slower. A second, previously unobserved, long-lived component is found in the decay of broad-band emission, comprising about 15% of the fluorescence intensity between 620 and 890 nm. Its lifetime is ⩾ 100 μs, coupling between some levels of the A 2 A 1 and X 2 B 1 states.

We describe sensitive opto-acoustic detection of chemical moieties with trace species selectivity far in excess of the selectivity available via the standard opto-acoustic approach. Rejection of typical interfering signals such as window and “dry-gas” absorptions, electronic pick-up, etc. is achieved by simultaneous modulation (chopping) of the excitation laser and frequency modulation (Zeeman or Stark) of the desired absorption line. The ability of this scheme to discriminate against overlapping absorptions in the NO/H2O/buffer system is demonstrated. The measured discrimination ratio at ppmv levels of NO is 2×10−4 NO/H2O. Ultimate sensitivity for NO is expected to be ≈10 pptv.