Abstract: A method for helmet construction by applying vacuum and fluid-pressure technologies is disclosed. Different types and sizes of exterior and interior helmet shells are press-formed from general engineering plastics. Conventional adhesive is applied on the inside surface of the exterior shell for fastening the interior and exterior shells together to form an integral shell unit. The shell unit is set on the base of a vacuuming apparatus moulded to adapt and to receive the inside surface contour of the interior shell. The vacuuming apparatus and the shell unit setting thereon are placed inside a conventional plastic film bag for vacuuming clear of any air pockets in the space between the two shell layers. The vacuumed film bag containing the vacuuming apparatus and the shell unit is then submerged under heated fluid contained in an airtight and pressure-resistant vessel. Pressure is subsequently applied to the vessel to further pressurize and complete the fastening process of the interior and exterior shells.

Abstract: A plasma reactor process measurement instrument includes an input phase processor receiving wafer bias voltage, current and power and computing an input impedance, an input current and an input voltage to the transmission line; a transmission line processor for computing a junction admittance of a junction between the transmission line and the conductive grid from the input impedance, input current and input voltage and from parameters of the transmission line; a grid-to-ground transformation unit for providing shunt electrical quantities of a shunt capacitance between the grid and a ground plane; a grid-to-wafer transformation unit for providing load electrical quantities of a load capacitance between the grid and the wafer; and, a combined transformation processor for computing the at least one of the etch rate, plasma ion density and wafer voltage from the junction admittance, the shunt electrical quantities, the load electrical quantities and a frequency of the RF power generator.

Abstract: The invention is a rotatable cylindrical roll for heat sealing heat sealable materials that includes a heating zone for sealing the material and a cooling zone for supporting the newly formed seal. The device comprises a conductive zone and a resistive zone that are in electrical communication. The resistive zone comprises a cylindrical member having a circumferential band of resistive material disposed on its surface. The conductive zone comprises a cylindrical member having a plurality of conductive strips extending laterally across its surface that are in electrical communication with the resistive band. Current is applied via a brush to the conductive strips. Current flows from the conductive strips into the resistive band and exits through a conductive strip that is in contact with a ground. Current path through the resistive band defines the heating zone, and the cooling zone is defined by area of the resistant band outside the heating zone.

Abstract: An apparatus including a coke drum for coking hydrocarbon substances, a valve disposed near the bottom of the coke drum, and a discharge conduit for removing coke from the coke drum, wherein the discharge conduit is connected to the valve such that when the valve is open, the coke may be removed via the discharge conduit.

Abstract: A method and apparatus for sputter deposition in which both a pulsed DC power supply and an RF power supply apply power to the target in the sputter deposition equipment. The pulsed DC power supply provides an on cycle where power is applied to the target, and an off cycle, in which a reverse polarity is applied to the target. The application of the reverse polarity has the effect of removing any charge that may have built up on the surface of the target. This reduces the likelihood of arcing occurring on the surface of the target, which can degrade the quality of the film being deposited on the substrate. By applying RF power simultaneously with the pulsed DC power to the target, the ionization efficiency on the target surface is increased. This results in a greater amount of material being removed from the target surface more quickly.

Abstract: Embodiments of the invention may generally provide a small volume electrochemical plating cell. The plating cell generally includes a fluid basin configured to contain a plating solution therein, the fluid basin having a substantially horizontal weir. The cell further includes an anode positioned in a lower portion of the fluid basin, the anode having a plurality of parallel channels formed therethrough, and a base member configured to receive the anode, the base member having a plurality of groves formed into an anode receiving surface, each of the plurality of grooves terminating into an annular drain channel. A membrane support assembly configured to position a membrane immediately above the anode in a substantially planar orientation with respect to the anode surface is provided, the membrane support assembly having a plurality of channels and bores formed therein.

Abstract: A method and apparatus for processing a microfeature workpiece. In one embodiment, the apparatus includes a support member configured to carry a microfeature workpiece at a workpiece plane, and a vessel positioned at least proximate to the support member. The vessel has a vessel surface facing toward the support member and positioned to carry a processing liquid. The vessel surface is shaped to provide an at least approximately uniform current density at the workpiece plane. At least one electrode, such as a thieving electrode, is disposed within the vessel. In a further aspect of this embodiment, the thieving electrode can be easily removable along with conductive material it attracts from the processing liquid. The shape of the vessel surface, the current supplied to the thieving electrode and/or the diameter of an aperture upstream of the workpiece are changed dynamically in other embodiments.

Abstract: An electrodeionization apparatus is provided, in which enough electric current flows even when voltage applied between the electrodes is low, thereby sufficiently performing deionization. A single first cation exchange membrane, a single anion exchange membrane, a single second cation exchange membrane are arranged between a cathode and an anode so that a concentration-cathode compartment, a desalting compartment, a concentrating compartment, and an anode compartment are formed, in this order, between the cathode and the anode. The concentration-cathode compartment and the anode compartment are filled with a cation exchange resin, respectively. The desalting compartment is filled with a mixture of the cation exchange resin and an anion exchange resin. Fed into the anode compartment is raw water or deionized water. Water from the anode compartment is sent to the concentrating compartment and the concentration-cathode compartment sequentially.

Abstract: The present invention concerns a lining support comprising a plurality of conductive pads (12) associated with a shared addressing contact (18) and means of selecting at least one pad to be lined by electrochemical means among the plurality of pads. In accordance with the invention, the selection means comprise means (20) of shifting a polarisation voltage, connected between the shared addressing contact and at least one pad to be addressed. Application to the lining of conductive pads.

Abstract: In devices such as flat panel displays, an aluminum oxide layer is provided between an aluminum layer and an ITO layer when such materials would otherwise be in contact to protect the ITO from optical and electrical defects sustained, for instance, during anodic bonding and other fabrication steps. This aluminum oxide barrier layer is preferably formed either by: (1) partially or completely anodizing an aluminum layer formed over the ITO layer, or (2) an in situ process forming aluminum oxide either over the ITO layer or over an aluminum layer formed on the ITO layer. After either of these processes, an aluminum layer is then formed over the aluminum oxide layer.

Abstract: A carrier or substrate for a photoconductor to be used for the formation of an electrophotographic recording element, particularly an imaging drum for an electrophotographic printing press, wherein the carrier is made of a metal or a metal alloy, preferably of aluminum, is prepared wherein the surface of the carrier supporting the photoconductor, used to form a barrier layer, is oxidized, preferably by etching and/or anodizing. The oxidized surface of the barrier layer is sealed with a sealing material following oxidation, and a preservative or impregnating agent is used as the sealing material.

Abstract: A process for electroplating of metal utilizing a valve metal electrode substrate containing multiple coating layers is disclosed. A top coating layer of a valve metal oxide is applied over a first coating layer of an electrochemically active coating. The electrode may find use in an electroplating system containing organic substituents in which the consumption of the organic substituent is significantly decreased or in systems where it is desirable to suppress the oxidation of a species in an electrochemical cell.

Abstract: The present invention deals with the electrochemical synthesis of electrically conductive polymers in supercritical fluids, for example supercritical CO2. The use of the supercritical fluid as a solvent results in the reduction or elimination of hazardous reagents and environmentally hazardous waste, which was generated in the prior chemical synthesis techniques. The electrochemical approach eliminates the need to add a charge transfer agent as the electrode serves this purpose. The resulting polymers are characterized by high conductivities and distinctive surface morphology, which suggests that they may be more appropriate than the previous materials for certain applications (e.g., corrosion inhibition, optical applications, etc.).

Abstract: An analyzer measures the concentration of a specific component in a sample liquid supplied to a test piece equipped with first and second terminal parts. An analyzer (X1) includes a stage on which a test piece is placed, a first terminal (40a) for electrical connection with a first terminal part, a second terminal (40b) for electrical connection with a second terminal part, and an electric circuit (6) for measuring parameters required for calculating the concentration of a specific component. A check piece (4?), in place of the test piece, is placed on a stage to test the electric circuit (6). The test of the electric circuit (6) is performed based on a plurality of electric responses from the electric circuit (6) with a plurality of electric conditions applied to the check piece (4?).

Abstract: An alternative fuel source, preferably for use in a boiler, is provided. The fuel source is comprised of a partially hydrogenated vegetable oil and diesel fuel. Preferably, the partially hydrogenated vegetable oil has a Iodine Value (IV) ranging from approximately 50 to approximately 120.

Abstract: A reactor conduit discharges into a disengaging chamber that is directly connected to a separator. A dipleg of the separator is directly connected to the disengaging chamber or to an intermediate chamber which is in direct communication with the disengaging chamber.

Abstract: The essence of the method is that diesel fuel is heated in the process of periodical circulation in a closed circuit including a heat exchanger and a rotor-disc apparatus of open type in centrifugal force field of which processes of mechanical destruction and dispersion run in environment of sucked air with oxygen saturation, simultaneously with processes of separation and homogenization fine filtration is carried out at a filtering porous partition of hydrophobic material with purification fineness 3÷8 micron as well as filtration at a multilayer filter-reactor at temperature 25÷45° C. which comprises granules of multifunctional catalyst alkylating aromatic compounds and a layer of fill of powder of transitional metals or their oxides. Then the treated fuel is stabilized by adding additives on the basis of surface-active substances.

Abstract: A process for the hydrogenation of a hydrocarbon feed includes contacting a major amount of the hydrocarbon feed with hydrogen in a counter-current manner in a first reaction zone under hydrogenation reaction conditions in the presence of a hydrogenation catalyst in at least a first catalyst bed wherein a liquid effluent exits at a bottom end of the first reaction zone and a hydrogen-containing gaseous effluent exits at a top end of the first reaction zone, and contacting a minor portion of the hydrocarbon feed with said hydrogen-containing gaseous effluent in a co-current manner in a second reaction zone having a catalyst bed positioned to receive the hydrogen-containing effluent of the first reaction zone.

Abstract: A device is provided for connecting pipe parts between two compartments of a filtration unit for water of a swimming pool. The filtration unit has a filtration compartment submerged in the water and equipped with at least one filtration means and a pumping compartment situated outside of the swimming pool and equipped with at least one suction and return pump. The compartments are connected by a common part that straddles the walls of the swimming pool. The filtration means and pump or pumps are connected in combination with suction and return pipe parts, which have one part situated in the filtration compartment and one part situated in the pumping compartment. At the common connecting part, watertight connecting members are positioned between the suction and return pipe conduit parts, whose thickness is less than the diameter of the various pipe parts.

Abstract: A fluid cleaning filter of the present invention consists of a composite matrix composed of a pleated substrate 2 configured into a pleated shape and an active carbon-containing layer 3, wherein the pleated substrate 2 is made of polyurethane foam 2a having a three-dimensional network skeletal structure, and the composite matrix is configured into a cylindrical shape. A filtering medium layer 2b made of fibers is formed on the surface of the polyurethane foam 2a facing the active carbon-containing layer 3. The fibers of the filtering medium layer maybe electrostatically charged. The fluid cleaning filter exhibits good efficiency of dust collecting and deodorization even when a fluid flows through the filter at high rate.

Abstract: Porous polymeric membranes including Halar (poly (ethylene chlorotrifluoroethylene)) and related compounds and the methods of production thereof which avoid the use of toxic solvents. Preferred solvents, coating agents and pore forming agents are citric acid ethyl ester or glycerol triacetate. The membranes may be in the form of a hollow fiber or flat sheet, and may include other agents to modify the properties of the membrane, such as the hydrophilic/hydrophobic balance. Leachable agents may also be incorporated into the membranes.

Abstract: The invention relates to a method for biological treatment of water, wherein macromolecular carbohydrates are added to the water to be treated, optionally together with vitamins and other additives, whereby a great reduction in residues is already achieved after adding small amounts of macromolecular carbohydrates, for example 0.4 to 600 mg/kg BSB5,zw or 0.014 to 14 mg/kg dry activated sludge daily.

Abstract: The invention provides a method for treating waste water wherein organic and inorganic substances in waste water can be treated at high levels regardless of the concentration, and a unit itself can be made compact. The method of the invention is a method for treating waste water, which comprises treating waste water at 100° C. or less in the presence of oxygen and catalyst containing noble metal and active carbon and having pores, wherein the volume of pores having a radius of 40 ? or more and less than 100 ? is 0.05 ml/g or more.

Abstract: Process for treating lipophilic fluids employing filters, more particularly, multifunctional filters that are capable of removing as well as adding components to lipophilic fluids being filtered are provided by the present invention.

Abstract: Methods for removing arsenic from water by addition of inexpensive and commonly available magnesium oxide, magnesium hydroxide, calcium oxide, or calcium hydroxide to the water. The hydroxide has a strong chemical affinity for arsenic and rapidly adsorbs arsenic, even in the presence of carbonate in the water. Simple and commercially available mechanical methods for removal of magnesium hydroxide particles with adsorbed arsenic from drinking water can be used, including filtration, dissolved air flotation, vortex separation, or centrifugal separation. A method for continuous removal of arsenic from water is provided. Also provided is a method for concentrating arsenic in a water sample to facilitate quantification of arsenic, by means of magnesium or calcium hydroxide adsorption.

Abstract: A separator device including a vessel for separating water from oil. The separator device is provided with a measurer for measuring the temperature of the wall of the vessel.

Abstract: Processes and devices associated with reducing the amount of organic substances in a fluid are described. In one example method, oxidizing agents may be introduced into a local constriction of flow in a flow-through chamber as the fluid is flowed therethrough. Cavitation bubbles which contain and/or are associated with the oxidizing agents may form. Collapse of the cavitation bubbles may produce pulses of ultraviolet light, thereby ionizing the oxidizing agents, producing hydroxyl radicals, and degrading and/or oxidizing the organic substances in the fluid. An example device may include a flow-through chamber including a local constriction of flow, a port configured to introduce oxidizing agents into the local constriction of flow, and may include an area configured to collapse the cavitation bubbles, thereby initiating events leading to degradation and/or oxidation of organic substances in a fluid flowed through the device.

Abstract: A depth filter design is disclosed which has little if any open void area upstream of the media. Preferably, it also has little if any open void area downstream of the media as well. A preferred embodiment uses layers of stacked, fibrous media with several of the layers being separated from the others by spacers which serve to compress the media and to prevent the bypass of fluid around the media adjacent the inner wall of the housing. Several designs for attaching the end caps which allow for the compression of the media are also disclosed.

Abstract: A wafer-scale fabrication method for providing MEMS assemblies having a MEMS subassembly sandwiched between and bonded to a cap and a base is provided. The MEMS subassembly includes at least one MEMS device element flexibly connected to the MEMS assembly. The vertical separation between the MEMS device element and an electrode on the base is lithographically defined. Precise control of this critical vertical gap dimension is thereby provided. Fabrication cost is greatly reduced by wafer scale integration.

Abstract: A selective etching method with lateral protection function is provided. The steps includes: (a) providing a substrate; (b) forming a plurality of tunnels; (c) forming a lateral strengthening structure at a peripheral wall of the tunnels; (d) removing a bottom portion of the lateral strengthening structure, and a part of the substrate by an etching process so as to form a lower structure and expose an unstrengthened structure; and (f) etching the unstrengthened structure laterally so as to form an upper structure.

Abstract: The invention relates to a method for forming silicon atomic force microscope tips. The method includes the steps of depositing a masking layer onto a first layer of doped silicon so that some square or rectangular areas of the first layer of doped silicon are not covered by the masking layer, etching pyramidal apertures in the first layer of doped silicon, removing the masking layer, depositing a second layer of doped silicon onto the first layer of doped silicon, the second layer of doped silicon being oppositely doped to the first layer of doped silicon and etching away the first layer of doped silicon. Further steps may be added to form the atomic force microscope tips at the end of cantilevers.

Abstract: Methods treating razors blade cutting edges having an adherent polyfluorocarbon coated thereon are described. The coated razor blade edges are treated with a solvent, which partially removes the coating from the razor blade edge. Addition of an antioxidant to the solvent improves the effectiveness of the treatment.

Abstract: A fast heat rise resistor comprising a substrate, a foil bridge on the surface of the substrate, the foil bridge having an elevated portion and a contact portion, the elevated portion above the substrate, the contact portion in contact with the substrate, a conductive layer attached to the contact portion of said foil bridge. The activation energy and/or response time is reduced as the foil bridge is suspended over the substrate. Another aspect of the invention include a method of manufacturing the foil bridge and application to autoignition vehicle airbags.

Abstract: A method for manufacturing a magnetic recording medium is provided, which can efficiently manufacture a magnetic recording medium that includes a recording layer formed in a concavo-convex pattern, has a sufficiently flat surface, and provides good recording and reproduction precision. The method includes: a non-magnetic material filling step of depositing a non-magnetic material over a recording layer formed in a predetermined concavo-convex pattern over a substrate, thereby filling a concave portion of the concavo-convex pattern with the non-magnetic material; and a flattening step of removing the excess part of the non-magnetic material above the recording layer by ion beam etching to flatten the surfaces of the non-magnetic layer and the recording layer.

Abstract: A method for avoiding plasma arcing during a reactive ion etching (RIE) process including providing a semiconductor wafer having a process surface for depositing a dielectric insulating layer; depositing at least a portion of a dielectric insulating layer to form a deposition layer according to plasma assisted chemical vapor deposition (CVD) process; treating the deposition layer portion with a hydrogen plasma treatment to reduce an electrical charge nonuniformity of the deposition layer including applying a biasing power to the semiconductor wafer; and, carrying out a subsequent reactive ion etching process.

Abstract: An antifreeze composition and method of use provides safety and protection for potable water systems in RVs, vacation homes, swimming pools and raw water cooled marine engines against freeze damage. The antifreeze composition includes propylene glycol, a sorbitol surfactant having a high Hydrophilic Lipophilic Balance (HLB) number and water. The preferred sorbitol surfactant consists of food grade polyoxyethylene (20) sorbitan monooleate. By directing the antifreeze composition into these water systems, freeze damage is prevented even when the temperature drops to extremely low levels.

Abstract: A first chemical mechanical polishing (CMP) slurry includes a polishing agent, an oxidant, a pH control additive, and an oxide film removal retarder which reduces a removal rate of the silicon oxide film. A second chemical mechanical polishing (CMP) slurry includes a polishing agent, an oxidant, a pH control additive, an oxide film removal retarder which reduces a removal rate of silicon oxide, and a defect prevention agent which inhibits scratch defects and/or corrosion defects at a surface of an aluminum film. In a one-step CMP process, either of the first or second slurry is used throughout CMP of an aluminum layer until an upper surface of an underlying silicon oxide layer is exposed. In a two-step CMP process, the first slurry is used in an initial CMP of the aluminum layer, and then the second slurry is used in a subsequent CMP until the upper surface of the underlying silicon layer is exposed.

Abstract: To minimize the variability in the emitted light color and improve the unevenness of color tone, a light emitting device comprises a light emitting element and a fluorescent substance that is excited by the light emitting element, wherein the light emitting element has an emission spectrum in a region from ultraviolet to visible light of short wavelengths, and the fluorescent substance has an emission spectrum that includes two or more emission peaks with at least two peaks of the two or more peaks being in the relation of complementary colors of each other.

Abstract: A method for converting hydrocarbon fuels to hydrogen and carbon monoxide through catalytic partial oxidation is described. The process comprises a reactor containing both an electrically heated catalyst as a start-up device and novel-metal-washcoated metallic monolith catalysts and a heat exchanging device. The partial oxidation reaction becomes ignited in less than 1.5 minute when the gaseous hydrocarbon fuel and oxygen-containing gas mixture is in contact with an electrically heated catalyst. The reaction takes place over the metallic monolith catalyst washcoated with noble metal (typically Pd/alumina-cerium oxide). The near complete conversion of hydrocarbon fuels with high hydrogen and carbon monoxide selectivities is achieved by preheating the feed mixture heat-exchanged with hot product gas stream.

Abstract: A process for making an aerogel-electrolyte-metal composite includes contacting an aerogel with an electrolyte to form an aerogel-electrolyte composite; contacting the aerogel-electrolyte composite with a metal precursor to form an aerogel-electrolyte-precursor composite; and converting the metal precursor of the aerogel-electrolyte-precursor composite to metal crystals to form the aerogel-electrolyte-metal composite. In addition, an aerogel-electrolyte-metal composite is formed by the process, wherein the average longest dimension of the metal crystals is about 1 to about 3 nanometers, and wherein the metal crystals are about 30% to about 100% dispersed.

Abstract: Method for preparing a semi-conductive ceramic material, wherein: in a receptacle containing a liquid, there are mixed from 30 to 90% of a conductive phase based on Z1-xMxCrO3 for 0?×?0.3, with Z being an element of the lanthanide group or a mixture of elements of this type, and M being calcium, strontium, magnesium, aluminum, titanium, yttrium or a mixture of two or more of these elements; from 8 to 60% of an insulating phase based on fine grains of alumina or tabular alumina or mullite or a mixture of two or more of these compounds; and from 0 to 10% of sintering additives; operations are carried out for milling, drying and sieving this mixture; this mixture is pressed; and this mixture is sintered in order to obtain a ceramic material having a porosity less than or equal to 25%.

Abstract: The present invention relates to a non-linear optical material having a dendrimer structure; and, more particularly, to a non-linear optical material having organic chromophores at the ends and formed based on ester linkages and/or ether linkages. Since the non-linear optical material of the present invention is formed based on ester linkages and/or ether linkages, it is very stable. Also, because it is a dendrimer structure, it has the properties of a polymer while having a strong connection ability at the ends, and this makes the non-linear optical material easily adopt organic chromophores easily. As it is stable thermally and optically, it can be applied to optical communication usefully.

Abstract: The invention related to a photochromic polymeric composition comprising a polymer matrix and a photochromic compound which is an adduct comprising a photochromic moiety and at least one pendant oligomer group to provide a rate of fade of the photochromic polymeric composition which is significantly changed when compared with the corresponding composition comprising the photochromic compound without said pendent oligomer. The invention also relates to a photochromic compound which is an adduct comprising a photochromic moiety and at least one pendent oligomer.

Abstract: The invention is directed to a system which allows for the rapid application of a water immobilizing dispersion in sufficient quantities to increase the fire protective and wetting characteristics of water. This system also increases the evaporative cooling and quenching effects of water. The primary constituents of the composition of this system are water, purified Attapulgite clay, and an environmentally safe salt, e.g., magnesium sulfate.

Abstract: A method of making a lid for a casket comprises providing tooling configured to produce a one-piece, unitary casket lid having a crown, a pie, a rim and a header, providing settable material from which to mold the lid, molding the settable material with the tooling, permitting the settable material to set thereby producing a one-piece, unitary casket lid having a crown, a pie, a rim and a header, and adhesively applying a wood veneer sheet to at least a portion of the lid. The veneer sheet can be applied with either a membrane press or a profile wrapping machine.

Abstract: An auxetic material, which has a negative Poisson ratio so that it has the property of expanding or contracting transversely to a direction in which it is extended or compressed, is made in filamentary or fibrous form. A suitable process involves cohering and extruding heated polymer powder so that the cohesion and extrusion is effected with spinning to produce auxetic filaments. Typically the powder is heated to a temperature sufficient to allow some degree of surface melting yet not high enough to enable bulk melting.

Abstract: This invention relates to a method for coating an elastomeric component with a coating that has a low coefficient of friction and the articles formed by the method. The method includes preparing an elastomeric coating; applying the coating to a substrate; contacting the coated substrate with an elastomeric compound; and heating the elastomeric compound and the coated substrate under pressure to bond the coating to the elastomeric compound and form a coated elastomeric component.

Abstract: A mold for molding semiconductor devices mounted on a package substrate is provided. The mold comprises a top mold and a bottom mold. The top mold has a top runner, at least a first dummy runner and a plurality of mold cavities. The first dummy runner connects with the top runner and the top runner extends into a space between the mold cavities. The mold cavities for accommodating the semiconductor devices are connected to the top runner. The bottom mold has a bottom runner and at least a second dummy runner. The second dummy runner connects with the bottom runner. The second dummy runner is above but separated from the first dummy runner by the package substrate.

Abstract: A cylindrical element is manufactured by a process which includes depositing successive layers of thermoplastic materials in a cycle by rotation moulding, or by a technique enabling a deposit of successive layers, the cycle including at least one deposit by rotation moulding or by a technique enabling deposit of successive layers at a temperature from 170 to 240° C. The cylindrical element contains at least one layer containing an ethylene-vinyl alcohol copolymer with a density at the above temperature of between 0.94 and 1.4, and a melt flow index of between 1.3 and 4.2 g/10 minutes.

Abstract: The present invention relates to a method for making an ablation transducer having a plurality of helical elements that can be operated out of phase to orient the acoustical energy beam forward or backward in the longitudinal direction. The transducers includes a cylindrical inner electrode, a cylindrical piezoelectric material disposed over the inner electrode, and a cylindrical outer electrode disposed over the cylindrical piezoelectric material. Spiral grooves are cut through at least the outer electrode separating the transducer into a plurality of functionally discrete helical transducer segments. The helical transducer segments can be operated independent from one another. An array of intertwined helical transducers arranged linearly along a helical axis are also contemplated.