Systems hybrid

Hybrid systems represent a group of resins which combine more than one generic class of polymer. The technique is akin to the surfactant free approach through which the phases are of different generic classes. 

The most widely used commercial techniques are the dispersed phase which is either acrylic or styrene acrylic and the continuous phase is either polyester or polyurethane, either of which has been modified so that they are water soluble. 

One typical example is a urethane-acrylic. The resultant resin combines the technical advantages of the urethane polymer to provide adhesion to low energy surfaces, impact resistance and solvent resistance, with the best features of acrylics, maiidy transparency and UV resistance, and, to some extent, cost. 

An important advantage of this technology is the benefit of being able to combine performance attributes to achieve specific end use performance specifications without need to resort to more expensive, speciality, functional monomers or post additives. 

Some commercial products derived by this route claim a degree of grafting during the polymerisation process which results in further improvements in film properties. 

Scaled-up elution chromatography and simulated countercurrent systems both have advantages and disadvantages. It makes sense to try to combine these two methods and develop hybrid systems that have some of the characteristics of both the other types. 

When several compounds in the feed are to be purified, the difficulty of the separation is controlled by the two components with the closest selectivities. Thus, the column length and the period of the feed pulse are chosen based on these key components. Other components will come out either much quicker or much slower than the key components. 

The time when the next pulse can be input is controlled by the difference between the retention times of the slowest and fastest components. Thus, total throughput is controlled by the easy to separate compounds. The easier the separation of these nonkey components the lower the throughput since the retention times of the fastest and slowest components will differ greatly. 

FIGURE 14.4-1 Column switching methods. Reprinted with permission from P. C. Wankat, Large-Scale Adsorption and Chromatography, CRC Press, Boca Raton, FL, 1986. 

Column switching is also useful instead of recycle for further separation of partially separated peaks. This is shown in Fig. 14.4-lC. Heart cuts which are pure are withdrawn at port 1 while the overlapping tails are sent to other columns for further separation. This is advantageous compared to recycle since the partial separation achieved in column A is retained when transfening columns. This procedure has been used in large-scale systems and can be combined with recycle as shown in Fig. 14.4-lD.  

Advanced power generation cycles that combine high-temper-ature fuel cells and gas turbines, reciprocating engines, or another fuel cell are the hybrid power plants of the future. As noted, these conceptual systems have the potential to achieve efficiencies greater than 70% and projected to be commercially ready by the year 2010 or sooner. The hybrid fuel cell/turbine (FC/T) power plant will combine a high-temperature, conventional molten carbonate fuel cell or a solid oxide 

The combination of the fuel cell and turbine operates by using the rejected thermal energy and residual fuel from a fuel cell to drive the gas turbine. The fuel cell exhaust gases are mixed and burned, raising the turbine inlet temperature while replacing the conventional combustor of the gas turbine. Use of a recuperator, a metallic gas-to-gas heat exchanger, transfers heat from the gas turbine exhaust to the fuel and air used in the fuel cell. 

There can be many different cycle configurations for the hybrid fuel cell/turbine plant. In the topping mode described above, the fuel cell serves as the combustor for the gas turbine, while the gas turbine is the balance of plant for the fuel cell, with some generation. In the bottoming mode, the fuel cell uses the gas turbine exhaust as air supply, while the gas turbine is the balance of plant. In indirect systems, high-temperature heat exchangers are used. 

Initial systems will be less than 20 MW, with typical system sizes of 1 to 10 MW. Future systems, in the megawatt class size, will boost efficiency even further by combining two solid oxide fuel cell modules with more advanced gas turbines and introducing sophisticated cooling and heating procedures. 

Hybrid plants are projected to cost 25% below comparably sized fuel cells and be capable of producing electricity at costs 

The component techniques of soft computing are not competitive, but complementary. Much research has been done to study the ways this complementarity can be exploited. Each of the components has features to offer a potential partnership. Systems that have such a partnership are called hybrid systems . Fuzzy logic uses the concept of computing with words, it deals with imprecision and information granularity and is an important tool for approximate reasoning. Neural networks learn and adapt. Genetic algorithms make use of a systemized random search and are an important tool for optimization. These three may be combined in different ways, as described below. 

Many types of combinations between fuzzy systems and neural networks have been proposed and studied. In what follows, we use the definitions and classification proposed by Detlef Nauck, from the Department of Computer Science, Technical University of Braunschweig, GermanyA neuro-fuzzy or neural fuzzy system is a combination of neural networks and fuzzy systems in such a way that neural networks are used to determine parameters of fuzzy systems. The main intention of a neuro-fuzzy approach is to create or improve a fuzzy system by means of neural network methods. The system should always be interpretable in terms of fuzzy if-then rules. A fuzzy 

Fuzzy methods are also used to enhance the learning capabilities or performance of a neural network. This can be done by using fuzzy rules to change the learning rate, or by creating a network that works with fuzzy inputs. 

A neural network and a fuzzy system may work together on the same task, but without influencing each other, that is, neither system is used to determine parameters of the other. Usually, the neural network preprocesses the inputs or postprocesses the outputs of the fuzzy system. 

A neural network may also be used to determine the parameters of a fuzzy system. After the learning phase, the fuzzy systems work without the neural network. Cooperative models use the following approaches (a) learn fuzzy sets off-line (b) learn fuzzy rules off-line (c) learn fuzzy sets on-line (d) learn rule weights. 

Dense carbon dioxide represents an excellent alternative reaction medium for a variety of polymerization processes. Numerous studies have confirmed that CO2 is a potential solvent for many chain growth polymerization methods, including free-radical, cationic, and ring-opening metathesis polymerizations. Carbon dioxide has also been demonstrated to be an effective solvent for step-growth polymerization techniques. Advances in the design and synthesis of surfactants for use in CO2 will allow compressed CO2 to be utilized for a wide variety of polymerization systems. These advances may enable carbon dioxide to replace hazardous VOCs and CFCs in many industrial applications, making CO2 an enviromentally responsible solvent of choice for the polymer industry. 

A direct, straightforward synthesis involves acid-catalysed reactions of carbonyl compounds and furan. Ackman et al. optimized the use of furan and acetone in 1 2 ratio and evolved the first ever synthesis of octamethylcalix[4]furan (4) (55JOC1147). 

In another version of the single-step approach, ZnCl2/HCl catalysed cyclocondensation of commercially available furfuryl alcohol uniquely provides the parent calix[4]furan (7) in 1% yield and the method on comparison with subsequently reported other methods has been advocated as a convenient preparative scale approach (89AGE1651). 

An indirect two-step synthetic methodology for calix[n]furans (C ) involves the formation of linear oligomers (L ) from furan and carbonyl compounds, followed by condensations of various L and carbonyl compounds or cyclization of an appropriate linear oligomer with a carbonyl compound. On the whole, this methodology constitutes a directed approach for a specified target but its utility depends largely on the availability of the precursor linear oligomers. 

A practical and compendious general route, directed towards both odd- and even-membered linear oligomers upto Lg, has been recently discovered by Rees et al. (2001JCS(P1)3297). It involves the use of L2 and L3 formed from furan and acetone (2 1) and basically the reactions of their metalated furan units 11 with an appropriate electrophilic carbamoyl derivative 12 of the furan ring to link furans and form ketones 13 which are converted to 14 employing Me2 Zn-Ti CI4. 

Hybrid linear tri- and tetra-oligomers possessing combinations of furan, thiophene or pyrrole have been obtained (2000TL2919, 2001T7323) by BFs-catalysed reactions of diols 18, and 22 with pyrrole, etc. The diols are obtained from reactions of bisanions of the parent heterocycles or their dimers with ketones. 

Schematic diagram describing a general HEV powertrain integrated with a supercapacitor. 

Energy Storage Requirements for Various Types of Hybrid Electric Vehicles [2] 

Type of Hybrid Driveline System Voltage (V) Usable Energy Storage Maximum Pulse Power at 90-95% Efficiency (KW) Cycle Life (Number of Cycles) Usable Depth-of- Charge 

The micro-hybrid electric vehicles are the simplest versions that improve fuel efficiency. Burke et al. [2] used a small electric motor and a module of 18 commercial carbon-carbon double-layer-based ESs. They demonstrated a 40% improvement in fuel economy with the Federal Urban Driving Schedule (FUDS) and an increase in engine efficiency of 30% in comparison to an ICE of 19%. 

Hybrid carbon ESs (Chapter 2) with larger energy densities of 8 to 12 Wh/kg were used in simulation testing for comparison. An unbalanced increase in power density (i.e., less than double) and reduced power efficiency impacted their suitability for micro-hybrids that rely on high-efficiency power. Charge-sustaining and plug-in hybrids appear to be more suitable applications. 

---

Hybrid systems. Depending on the problem to be solved, use can also be made of a combination of techniques leading to a hybrid system. For example, a rule-based system may use neural networks for solving classification subproblems (as is described in [Hopgood, 1993]), or a combination of a rule-based and a CBR system can be used as in the system for URS data interpretation described later in this paper. 

A brief description of this hybrid system appears in Chapter 20. For further information on the quadrupole or TOF instruments, see Chapters 25 and 26, Quadrupole Ion Optics and Time-of-Flight Ion Optics. ... 

Process Concepts. Hybrid systems involving gas-phase adsorption coupled with catalytic processes and with other separations processes (especially distillation and membrane systems) will be developed to take advantage of the unique features of each. The roles of adsorption systems will be to efficiently achieve very high degrees of purification to lower fouUng contaminant concentrations to very low levels in front of membrane and other separations processes or to provide unique separations of azeotropes, close-boiling isomers, and temperature-sensitive or reactive compounds. 

A newer hybrid system available commercially is the magnetic sector—TOF hybrid (38). The precursor ions can be selected with better than unit—mass resolution by msl and the product ion ions detected at high sensitivity by the TOF ms2 (39). 

Polyurethane sealant formulations use TDI or MDI prepolymers made from polyether polyols. The sealants contain 30—50% of the prepolymer the remainder consists of pigments, fiUers, plastici2ers, adhesion promoters, and other additives. The curing of the sealant is conducted with atmospheric moisture. One-component windshield sealants utili2e diethyl malonate-blocked MDI prepolymers (46). Several polyurethane hybrid systems, containing epoxies, siUcones, or polysulfide, are also used. 

Algorithmic stmcture of simulator EO, equation oriented HS, hybrid system SM, sequential modular and SMD, sequential modular, suitable for design. 

The most common form of energy deposition used for planar shock wave research has been electrical resistance heating of a metal foil which vaporizes, driving a flyer plate to a high velocity before it impacts a specimen. In a hybrid system incorporation both resistance vaporization and an electromagnetic push, velocities to 18 km/s are reported for kapton flyer plates which are... 

Depending on the specifics of the project, location, climatic conditions, engine type, and economic factors, a hybrid system utilizing a combination of the above technologies may be the best. The possibility of using fogging... 

Each type of mass spectrometer has its associated advantages and disadvantages. Quadrupole-based systems offer a fairly simple ion optics design that provides a certain degree of flexibility with respect to instrument configuration. For example, quadrupole mass filters are often found in hybrid systems, that is, coupled with another surface analytical method, such as electron spectroscopy for chemical analysis or scanning Auger spectroscopy. 

Hybrid systems of acrylics with other technologies have been reported. Aciylic and epoxy polymers can be coupled through the use of 2-methacryloloxyethyl phosphate. The phosphoric acid functionality reacts with epoxy and the methacrylate group copolymerizes with the acrylic backbone [ 145] (Scheme 14). 

In some hybrid systems, the generated vapor in a vented reaetion is high enough to remove suffieient latent heat to moderate or temper the runaway (i.e., to maintain eonstant temperature). This subsequently gives a smaller vent size. 

Vent areas and diameters of the vapor, gassy, and hybrid systems... 

Hybrid system Hybrid systems are those in which the total pressure is due to both vapor pressure and permanent gas. 

EJ-Haiwagi, M. M. (1993). Optimal design of membrane hybrid systems for waste reduction. Sep. Sci. TechnoL, 28(1-3), 283-307. 

Muralikrishnan, G., Crabtree, E., and El-Halwagi, M. M. (1996). Design of Membrane Hybrid Systems for Pollution Prevention." AIChE Spring Meeting, New Orleans, LA. 

The Two-Hybrid System to Identify Proteins Involved in Specific Protein-Protein Interactions... 

Chien, C.-X, et al., 1991. The two-hybrid system A method to identify and clone genes for proteins that interact with a protein of interest. Proceedings of the National Academy of Sciences U.S.A. 88 9578 — 9582. 

Toyota Press Infonnation. (1997). Toyota Hybrid System. Tokyo Toyota Motor Corporation, Planning Group, International Public Affairs Division. 

Hermance, D. (1999). The Toyota Hybrid System. Pres. At SAE TOPTEC, Hybrid Electric Vehicles Here and Now (27 May). 

Takaoka, T., et al. (1998). A High-Expansion—Ratio Gasoline Engine for the Toyota Hybrid System. Toyota Review 47 2). 

There are three potential types of OTEC power plants opcii-cyclc, closed-cycle, and hybrid systems. Open-cycle OTEC systems exploit the fact that water boils at temperatures below its normal boiling point when it is under lower than normal pressures. Open-cycle systems convert warm surface water into steam in a partial vacuum, and then use this steam to drive a large turbine connected to an electrical generator. Cold water piped up from deep below the oceans surface condenses the steam. Unlike the initial ocean water, the condensed steam is desalinated (free of salt) and may be collected and used for drinking or irrigation. 

The pressurized hybrid cycle provides the basis for the high electric efficiency power system. Applying conventional gas turbine technology, power system efficiencies in the 55 to 60 percent range can be achieved. When the pressurized hybrid system is based on a more complex turbine cycle— such as one that is intercooled, reheated, and recuperated—electric efficiencies of 70 percent or higher are projected. 

Leung, J. C., Vent Sizing for Gassy and Hybrid Systems, in Safety of Chemical Batch Reactors and Storage Tanks, Benuzzi, A. and Zaldivar,J. M. (ed), 299-310, Kluwer Academic Publishers, Dordrecht, April 1991. 

K. Kordesch, C. Fabjan, J. Daniel-Ivad, J. Oliveira, Zinc-carbon-hybrid systems, Power Sources Conf. Brighton, April 1997. 

In a solid-propellant rocket motor, the propellant is contained within the wall of the combustion chamber, as shown in Fig. 1. This contrasts with liquid systems, where both the fuel and oxidizing components are stored in tanks external to the combustion chamber and are pumped or pressure-fed to the combustor. In hybrid systems, one component, usually the fuel, is contained in the combustion chamber, while the other component is fed to the chamber from a separate storage tank, as in liquid systems. The solid-propellant motor also has an ignition system located at one end to initiate operation of the rocket. The supersonic nozzle affects the conversion of... 

---