Indirect field oriented control (IFOC) and direct torque control (DTC) have been widely commercialized in induction motor drives, with each being favored by its supporters. In this paper, the dynamic performance of these drives for an electric vehicle application is examined, and sensitivities to parameter variations affecting this dynamic performance are explored. Key performance measures include torque and speed transients. To achieve decoupling between the drive and the switching scheme, both drives are simulated in MATLAB/Simulink for different switching schemes. These schemes include space-vector pulse-width modulation (SVPWM), and hysteretic control for IFOC and DTC. DTC is also simulated with a switching table. Experimental results for some of these schemes are also presented. Results show that control performance is influenced by the switching scheme. It is shown that when IFOC and DTC are used with SVPWM, the torque response of IFOC is superior. These characteristics are verified by simulations. The work opens further discussion for the feasibility of applying IFOC in electric and hybrid-electric vehicles. 1 Nomenclature P: Number of poles r s : Stator resistance (Ω) r r : Rotor resistance (Ω) L m : Mutual inductance (H) L s : Stator inductance (H) L r : Rotor inductance (H) τ r = L r /r r (s) σ = (L s L r -L m 2 )/L r : Leakage factor (H) ς = (L s L r -L m 2 )/L m 2 : per-unit leakage factor i qs : Quadrature stator current (A) i ds : Direct stator current (A) i abcs : 3-phase stator current (A) v qs : Quadrature stator voltage (V) v ds : Direct stator voltage (V) v abcs : 3-phase stator voltage (V) T e : Electromechanical torque (N·m) T L : Load torque (N·m) θ e : Electrical angle (rad) ω e : Electrical frequency (rad/s) ω r : Rotor speed (rad/s) ω rm : Mechanical speed (rad/s) ω sl : Slip frequency (rad/s) 1 This work was supported in part by the U.S. Office of Naval Research under Award Number N00014-08-1-0397.λ qs : Quadrature stator flux linkage (V·s) λ ds : Direct stator flux linkage (V·s) λ qr : Quadrature rotor flux linkage (V·s) λ dr : Direct rotor flux linkage (V·s) λ s = : Stator flux magnitude (V·s) λ r = : Rotor flux magnitude (V·s)The superscript "*" denotes a command input. The superscripts "e" and "s" denote variables in the synchronous and stationary reference frames, respectively.

AC Corrosion ProtectionW hen one does a specific action and observes a specific result; then, the opposite action should cause the opposite result. This is an example of a linear response system. According to Newton's second law, a pulling force on the right side of an object will accelerate it toward the right. A pulling force on the left side, will accelerate that object toward the left. If the magnitudes of the forces are doubled, the acceleration will be doubled. What are the limitations of such linear responses? What happens when this fails? Let us choose an important chemical system to take a closer look: rusting steel structures-the corrosion of iron.Rusting occurs when iron or steel are in an oxidizing environment such as atmospheric oxygen and water. The metal turns into ferric rust, a soft red-brown compound. The degradation of metals by corrosion is a very common reaction for metals, because the oxide of the metal has a much lower energy state than the metal itself. Therefore, metals have a strong tendency to oxidize. The National Association of Corrosion Engineers estimates that the cost of corrosion of steel bridges, pipelines, steel embedded in concrete, and vehicles will exceed one trillion dollars in the United States in 2013 [1]. The most common corrosion protection methods are plating, painting, and application of enamel. However, the metal is unprotected when the coating is damaged by abrasion or when differences in the physical properties between the metal and the coating create cracks and detachments. Cathodic protection is a method to suppress corrosion if other methods fail. It suppresses corrosion by shifting the electric potential difference between the steel and the surrounding medium such that the metal is immune to oxidation.The first step of the corrosion process of steel in a wet environment is the oxidation of metalic iron to ferric ions,where the ferric ion is dissolved in water and the electrons remain in the metal. Ferric ions react with oxygen and water and can eventually turn into rust. However, if there are already many electrons on the metal surface this reaction is reversed and the metal is immune to corrosion. Figure 1(a) shows that for moderate pH values, iron is immune to corrosion if the electric potential of the metal is 0.85 V lower than the potential of the surrounding liquid.

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The economical production of flexible, chemically-functionalized carbon nanotube (CNT) electrodes is appealing for the manufacture of electronic textiles with integrated charge storage capability. In this paper, a commercial CNT sheet is treated with 0.02 M potassium permanganate at room temperature to accomplish in-situ deposition of manganese dioxide. The morphology, elemental oxidation states, and crystallinity of the modified CNT sheet are studied using SEM, EDX, XPS, and XRD. Manganese loading is varied from 4 to 20 weight-percent by tuning solution treatment time, and metal oxide hydration state is influenced by thermal annealing at 200 °C. Electrochemical measurements reveal that charge is stored not only via CNT-induced electrical double-layer capacitance, but also through metal oxide-mediated Faradic reactions. The MnO2-decorated CNT sheet exhibits a specific capacitance of 89.6 F/g at 1 A/g, a tenfold enhancement compared to pristine CNT sheet. Overall, this simplified processing approach holds promise for cost-effective incorporation of electrochemical capacitors into functional fabrics for energy-generation applications.

The U.S. Army Engineer Research and Development Center, Construction Engineering Research Laboratory (ERDC-CERL) is developing a new class of flexible, generative textile as a novel means of sustainable wind energy generation. Flexible, generative carbon nanotube (CNT)-based textiles may have excellent potential for electrical capacitive storage and reuse in conjunction with small-scale energy-harvesting systems, both from wind for fixed applications and from human locomotion. This paper describes the design and optimization of a three-layer generative textile composed of discrete layers for generation, distribution, and storage. Initial results suggest that improvement in the generation layer will provide the highest increase in overall performance. The output of the electromagnetic tests shows a power density of 0.17 mW/cm3. However, the efficiency can be significantly improved through increasing the voltage output of the generation layer from 20 mV to around 1V. In an analysis of the operational envelope, wind data collected locally at ERDC-CERL and at other sites around the world reveal close similarity in the probability distributions, which could allow for a practical engineering approach capable of harvesting the steady “ram” component in addition to a variable energy component of the wind. To further study the textile-wind interactions, a wind simulation environment is being developed and has been able to obtain reproducible wind speed data thus far.