A flash analog-to-digital converter (ADC) includes comparators that convert an analog input signal to a digital output signal. Offsets of these comparators introduce noise and can hurt the performance of the ADC. Thus, these comparators are calibrated using calibration codes. Conventional calibration methods determine these calibration codes by removing the ADC from an input signal. Otherwise, it is difficult to distinguish the noise from the signal in the calibration measurement. In contrast, an embodiment can determine the calibration codes while the ADC converts the input signal to a digital signal. Such an embodiment can be achieved by a frequency-domain technique. In an embodiment employing a frequency-domain power meter, an input signal can be removed from the power measurement. This removal enables accurate measurement of in-band noise without having the measurement be corrupted by input signal power.

An analog to digital converter includes an error integration circuit configured to receive an input charge from a detector and to integrate a difference between the input charge and one or more feedback charge pulses to create an error voltage. A quantizer is in operable communication with the error integration circuit and is responsive to the created error voltage. An accumulator having a mantissa component and a radix component is in operable communication with the quantizer. A charge feedback device in operable communication with the quantizer and the radix component of the accumulator. The charge feedback device is configured to generate the one or more feedback charge pulses proportional to the radix component of the accumulator and an output of the quantizer. Digital focal plane read out integrated circuits including the analog to digital converter are also disclosed.

A probabilistic digitizer for extracting information from a Josephson comparator is disclosed. The digitizer uses statistical methods to aggregate over a set of comparator readouts, effectively increasing the sensitivity of the comparator even when an input signal falls within the comparator's gray zone. Among other uses, such a digitizer may be used to discriminate between states of a qubit.

The disclosure relates to a circuit for stabilizing a digital-to-analog converter reference voltage. One example embodiment is a circuit for stabilizing a voltage on a reference node. The circuit includes a digital-to-analog converter that includes an array of capacitors and arranged for: receiving an input voltage via an input node, receiving a voltage via a reference node and a digital-to-analog code via a controller node, and outputting a digital-to-analog output voltage. The circuit also includes a capacitive network on the reference node comprising a fixed capacitor arranged to be pre-charged to an external reference voltage and a variable capacitor arranged to be pre-charged to an external auxiliary voltage. Further, the circuit includes a measurement block. In addition, the circuit includes a calibration block arranged for determining an updated setting of the variable capacitor based on the digital-to-analog code and the measured voltage on the reference node.

For continuous-time multi-stage noise shaping analog to digital converters (CT MASH ADCs), quantization noise cancellation often requires estimation of transfer functions, e.g., a noise transfer function of the front end modulator. To estimate the noise transfer function, a dither signal can be injected in the front end modulator. However, it is not trivial how the dither signal can be injected, since the dither signal can potentially leak to the back end modulator and cause overall noise degradation. To address some of these issues, the dither signal is injected post the flash analog to digital converter (ADC) of the front end modulator. Furthermore, dummy comparator structures can be used to synchronize the dither with the quantization noise of the targeted flash ADC.

A circuit and a method for converting an analog signal to a digital value representation is disclosed. In one aspect, the circuit includes an incremental sigma-delta analog-to-digital converter (ADC). The circuit further includes a first input line for providing a primary analog signal representing a sensor measurement to the incremental sigma-delta ADC. The circuit further includes a second input line for providing a secondary analog signal to the incremental sigma-delta ADC. The incremental sigma-delta ADC receives the primary and secondary analog signals during a first period (TADC1) and a second period (TADC2), respectively. The circuit further includes a filter configured to weight the digital values in a sequence of digital values output by the incremental sigma-delta ADC, and to output a single digital value representing the sensor measurement.

A remote control for a wireless load control system, the remote control comprising: a housing having a front surface and an outer periphery defined by a length and a width; an actuator provided at the front surface of the housing; a wireless transmitter contained within the housing; and a controller contained within the housing and coupled to the wireless transmitter for causing transmission of a wireless signal in response to an actuation of the actuator, the wireless transmitter and the controller adapted to be powered by a battery contained within the housing; wherein the length and the width of the housing are slightly smaller than a length and a width of a standard opening of a faceplate, respectively, such that the outer periphery of the housing is adapted to be received within the standard opening of the faceplate when the housing and the faceplate are mounted to a vertical surface.

The present disclosure pertains to systems and methods for monitoring a plurality of analog-to-digital converters. In one embodiment, a plurality of input channels may each be in communication with a different phase of a three-phase electric power delivery system. The input channels may be configured to receive analog signals from the different phases. A composite signal subsystem may be configured to generate a composite signal based on the plurality of input channels. An analog-to-digital converter subsystem may be configured to produce a digitized representation of each of the plurality of input channels and a digitized representation of the composite signal. An analog-to-digital converter monitor subsystem may identify an error in the analog-to-digital conversion based on the digitized representation of the composite signal and the digitized representations of the plurality of input channels.

A system of systems to monitor data for carbon flux, for example, at scales capable of managing regional net carbon flux and pricing carbon financial instruments is disclosed. The system of systems can monitor carbon flux in forests, soils, agricultural areas, body of waters, flue gases, and the like. The system includes a means to identify and quantify sources of carbon based on simultaneous measurement of isotopologues of carbon dioxide, for example, industrial, agricultural or natural sources, offering integration of same in time and space. Carbon standards are employed at multiple scales to ensure harmonization of data and carbon financial instruments.

A liquid separator system having a gas phase zone, an aqueous phase zone and a denser liquid zone is used to separate mixtures of fluids. The separator can be used for separating molten sulfur from liquid redox solution or reslurry water. The system includes a vessel with a top part and a bottom part. The vessel has a larger diameter at the top part than at the bottom part. The system also includes an inlet for introducing a redox solution or reslurry water and molten sulfur, which is denser than redox solution or reslurry water, into the vessel. An outlet near the bottom part of the vessel allows a flow of the molten sulfur from the vessel. An interface control structure senses an interface level between the redox solution or reslurry water and the molten sulfur, and the interface control structure controls the flow of molten sulfur from the outlet. The interface control structure is adjusted to optimally alter the vertical height of the interface level within the vessel so that the residence time of the molten sulfur in the vessel does not decrease as the sulfur production throughput decreases, and so that the interface area of the molten sulfur and the redox solution is reduced as the sulfur throughput decreases. A pressure controller monitors the pressure in the vessel and adds or removes gas from a gas phase zone in the vessel to maintain a predetermined pressure regardless of the vertical height of the interface.

A process is provided for recovering sodium chloride crystals and sodium carbonate decahydrate crystals from a concentrated brine that results from a gas mining operation where gas and produced water is recovered and the produced water constitutes a brine. An initial pre-concentration process is carried out where the brine is concentrated and in the process carbon dioxide is removed from the brine and at least some sodium bicarbonate is converted to sodium carbonate. In one process, the concentrated brine is directed to a sodium chloride crystallizer where the brine is heated and further concentrated to form sodium chloride crystals which are separated from the brine to yield a product and wherein the resulting brine is termed a first mother liquor. The first mother liquor is then directed to a sodium carbonate decahydrate crystallizer where the first mother liquor is cooled and concentrated resulting in the formation of sodium carbonate decahydrate crystals and a second mother liquor. The second mother liquor is split into two streams where one stream is directed back to the sodium chloride crystallizer while the other stream is wasted or further treated.

Method for producing a uranium concentrate in the form of solid particles, by precipitation from a uranium-containing solution using a precipitating agent, in a vertical reactor comprising a base, a top, a central part, an upper part, and a lower part, the solid particles of the uranium concentrate forming a fluidized bed under the action of a rising liquid current which circulates from the base towards the top of the reactor successively passing through the lower part, the central part and the upper part of the reactor, and which is created by introducing a liquid recycling current (flow) at the base of the reactor, said liquid recycling current being tapped at a first determined level (A) in the upper part of the reactor and sent back without settling to the base of the reactor, excess liquid being also evacuated via an overflow located at a second determined level (B) in the upper part of the reactor; a method in which the upper limit (C) of the fluidized bed of solid particles is controlled so that it is positioned at a level below the first and second determined levels.

The present invention relates to a process for the wet production of granules from powdered materials, in particular raw materials for the production of glass. The process of the invention comprises the following successive steps: (i) the powdered materials to be granulated are divided into at least two portions: a first portion and a second portion; (ii) a binder liquid is added to the first portion of powdered materials; (iii) the first mixture thus obtained is agglomerated in the granulator in order to obtain granules (a); (iv) the second portion of powdered materials is added to the granulator; and (v) the new mixture obtained is agglomerated in the granulator in order to obtain granules (b). This sequenced granulation process allows granules to be obtained that have a degree of moisture that assures their stability and their ease of handling eliminating the drying step.

The present invention relates to means and methods for producing crystals or crystalline substances. In particular, crystals or crystalline substances which are useful as pharmaceutical ingredients can be manufactured.

A rotating knife is disclosed for disintegrating a crystal bed formed in a washing column for processing suspension of solid particles in a liquid. The rotating knife is provided with a spoke support. The spoke support comprises at least two spokes. The relative angle of the spokes is between approximately 20° and approximately 80°.

Disclosed herein is a method of fabricating a CIS or CIGS thin film, comprising: forming, on a substrate, a seed particle layer comprising copper-indium-compound seed particles comprising copper (Cu); indium (In); and at least one selected from the group consisting of gallium (Ga), sulfur (S) and selenium (Se),applying, on the seed particle layer, a water-soluble precursor solution comprising: a water-soluble copper (Cu) precursor;a water-soluble indium (In) precursor; andat least one selected from the group consisting of a water-soluble gallium (Ga) precursor, a water-soluble sulfur (S) precursor and a water-soluble selenium (Se) precursor, and forming a thin film at high temperature.

This invention refers to a novel process to obtain magnesium hydroxide and sodium sulfate from a solid raw material, which contains sodium and magnesium soluble salts, preferably in the form of sulfates, coming from a natural source or as a byproduct of an industrial process. The process consisting in the conditioning of the raw material to guarantee the correct concentrations of sodium and magnesium sulfates that is subjected to a salting-out crystallization when mixed with sodium sulfate obtaining sodium sulfate; the resulting solution is subjected to an alkali treatment to precipitate the magnesium hydroxide and the mother liquor is fed to a regeneration stage of the alkali used in the precipitation of the magnesium hydroxide as well in the sodium sulfate solution for the crystallization. The crystallization can be performed as a multistage process countercurrent to increase the purity of sodium sulfate.

Method for the production of a coarse-grained ammonium sulphate product by crystallization and installation for carrying out the method from an ammonium sulphate solution in a DTB type crystallizer having an internal suspension circuit and a clarifying zone, from which a clarified partial flow of solution is constantly drawn off into an external circuit, is heated in a heat exchanger to dissolve the solids contained therein and is guided back as a clear solution into the lower region of the crystallizer. A fine crystal suspension flow is drawn off from the clarifying zone as a further partial flow and guided back into the internal circuit of the crystallization stage without any previous dissolution of the solid proportion contained therein.

The invention provides a process comprising: a crystallization step of concentrating and crystallizing the ammonium salt of sulfuric acid from an aqueous solution that contains the ammonium salt of sulfuric acid; a solid-liquid separation step of solid-liquid separating the ammonium salt of sulfuric acid obtained in the crystallization step, and a crystallization mother liquid recycling step of recycling a crystallization mother liquid obtained in the solid-liquid separation step to at least one step selected from the crystallization step and one or more steps that precede the crystallization step, in which not all of the crystallization mother liquid is recycled.

A method of producing a titanium dioxide pigment is provided. Also provided is a method of improving the processability of titanium dioxide particles without adversely affecting the rheological properties of the titanium dioxide particles.

A method of processing bundles of carbon nanotubes (CNTs). Bundles of CNTs are put into a solution and unbundled using sonication and one or more surfactants that break apart and disperse at least some of the bundles into the solution such that it contains individual semiconducting CNTs, individual metallic CNTs, and remaining CNT bundles. The individual CNTs are separated from each other using agarose bead column separation using sodium dodecyl sulfate as a surfactant. Remaining CNT bundles are then separated out by performing density-gradient ultracentrifugation.

Mineral, cosmetic, pharmaceutical, agricultural, nutraceutical, and other compositions are produced using a mineral composition containing minimal concentrations of cadmium, lead, arsenic, and mercury and containing relatively high concentrations of micro and macro mineral elements, of rare earth elements, of calcium, and of silica. The mineral concentrations are produced by processing naturally occurring clay soil to concentrate mineral elements naturally occurring in the soil.

A method of producing a surface-treated carbon black powder dispersion includes subjecting carbon black fine particles having a volume average particle size of 100 nm to 20 μm to wet granulation and drying by heating to obtain granulated carbon black having a hardness of 12 cN or less and a pH of less than 7, grinding the granulated carbon black to obtain a ground product having a volume average particle size of 20 nm to 20 μm, and subjecting the ground product to wet oxidization in an aqueous medium. The resulting surface-treated carbon black powder dispersion exhibits excellent print density, print quality, discharge stability, and storage stability when used as an inkjet printer aqueous black ink.

This invention relates to novel methods for affecting, controlling and/or directing various crystal formation, structure formation or phase formation/phase change reaction pathways or systems by exposing one or more components in a holoreaction system to at least one spectral energy pattern. In a first aspect of the invention, at least one spectral energy pattern can be applied to a crystallization reaction system. In a second aspect of the invention, at least one spectral energy conditioning pattern can be applied to a conditioning reaction system. The spectral energy conditioning pattern can, for example, be applied at a separate location from the reaction vessel (e.g., in a conditioning reaction vessel) or can be applied in (or to) the reaction vessel, but prior to other (or all) crystallization reaction system participants being introduced into the reaction vessel.

A process for producing granules containing one or more complexing agent salts of the general formula from an aqueous starting solution, containing the one or more complexing agent salts in a concentration of from 10 to 80% by weight, based on the total weight of the aqueous starting solution, in a jet apparatus.

The present invention relates to compositions and methods to increase the output of a high quality product from the precipitation liquor crystallization process exemplified through the aluminum hydroxide recovery processes such as the Bayer process. The invention is a method of increasing the size of precipitates from a liquor. The invention in one embodiment relates to the use of a crystal growth modifier compositions added to the precipitation process to increase the particle size distribution of the precipitated alumina trihydrate.

Aspects of the present invention relate to a process to obtain potassium chloride that includes submitting brine to concentration, separating brine after concentration, resulting in a first solid content and a first liquid content, cooling the first liquid content, separating the first liquid content after cooling, thus resulting in a second solid content and a second liquid content, enriching the second solid content, and separating the second solid content after enrichment, thus resulting in a third solid content and a third liquid content. Aspects of this process are environmentally safe, as the process includes stages using solvents and equipment which does not harm the environment. Moreover, aspects of this process present a significant energy consumption reduction.

The present invention relates to a process for the preparation of granules comprising the steps of: providing a granulation zone comprising particles, the particles being kept in motion; providing a first feed stream comprising a liquid composition into the granulation zone, the liquid composition being applied onto or over the moving particles in the granulation zone; withdrawing a product stream comprising granules from the granulation zone, the granules being the result of layered growth of the moving particles in the granulation zone; wherein a second feed stream comprising granulation nuclei is fed into the granulation zone, wherein the granulation nuclei have a particle size distribution characterized by a standard deviation of the particle size that is less than 15% of the mean particle size, and wherein the second feed stream comprises between 0.05 wt % and 50 wt % of the product stream.

A process for the production of sodium carbonate and sodium bicarbonate out of trona, comprising crushing trona ore and dissolving it in a leaching tank containing a solution comprising sodium carbonate and sodium bicarbonate, and an additive selected from the group consisting of: phosphates, phospholipids, carboxylates, carboxilic acids, and combinations thereof, saturated in sodium bicarbonate, in order to produce solid particles suspended in a production solution comprising sodium carbonate, the solid particles containing insoluble impurities and at least 65% by weight of sodium bicarbonate. The solid particles are separated from the production solution containing sodium carbonate. At least part of the production solution containing sodium carbonate is taken out of the leaching tank.

A method for making an agglomerate of an ore is disclosed. The method comprises contacting the ore with an acid solution and a stucco binder. The stucco binder may include calcium sulfate hemihydrate. The ore agglomerate may include ore, acid solution, and stucco-derived gypsum.

A system and a method are provided that take a potentially dangerous waste product and process the product to create a marketable asset. The system and method are configured to create “tb” from “tbgs” by removing the volatility that exists in the “tbgs.” The resultant “tb” may be substantially non-volatile.

An object of the present invention is to provide a method for producing composite carbon fibers in which two or more carbon fibers are dispersed in a nearly homogenous state, the composite carbon fibers capable of being easily dispersed in a matrix such as a resin without leaving aggregate, and imparting low resistance. Disclosed is a method for producing composite carbon fibers, which comprises imparting a cavitation effect to slurry containing 6% by mass or less of two or more carbon fibers each having a different average fiber diameter under a pressure of 100 MPa or more and less than 245 MPa thereby to form a composite.

The present invention relates to a process for the preparation of articles of manufacture made of or based on sulphur, which comprises cooling of liquid sulphur in a volume of containment until the sulphur mass solidifies and forming of the product, characterized in that elastic pressure waves are applied to the cooling mass of liquid sulphur to produce a crystalline suspension of solid sulphur in liquid sulphur.

A floating salt farm in which its purpose is to produce crystallized salt and bittern at offshore locations through the evaporation process using extracted seawater. The floating salt farm components can be consisted of a seawater tank, an evaporator tank, a heating tank, a deposit tank, a storage tank, and photovoltaic panels, which these components are installed onto the buoyant foundation. The evaporator tank component can consist of an evaporator plate and an evaporator bin. The evaporator plate, which captures the produced crystallized salt during the evaporation process, has a sieve surface. The contents inside the evaporator bin can affect the properties of the produced crystallized salt and bittern, such as their mineral compositions, during the evaporation process. The seawater can be extracted from desired water depths and/or in the proximity of volcanic sites, in which the seawater can have affected mineral compositions due to volcanic activity.

Process for the combined regeneration of at least two soluble salts contained in a residue of an industrial process comprising heavy metals, comprising: adding an amount of reactive aqueous solution needed to completely dissolve the salts which are desired to be regenerated to the residue; subjecting the resulting aqueous suspension to a separation to obtain an aqueous production solution on the one hand and insoluble impurities on the other hand, which are removed; successively subjected the aqueous production solution to at least two selective crystallization steps intended to crystallize, separately, the at least two soluble salts which are desired to be regenerated, which are washed, dried and regenerated separately; and adjusting the concentration of at least one of the soluble salts to be regenerated in the aqueous production solution, at the moment when such solution is subjected to the step of crystallization of this salt, to give rise to the selective crystallization of this salt, by addition of a controlled amount of this salt to the aqueous production solution upstream of the crystallization step.

Titanium dioxide which includes particles having a large major-axis length in a large proportion and comprises columnar particles having a satisfactory particle size distribution. A titanium compound, an alkali metal compound, and an oxyphosphorus compound are heated/fired in the presence of titanium dioxide nucleus crystals having an aspect ratio of 2 or higher to grow the titanium dioxide nucleus crystals. Subsequently, a titanium compound, an alkali metal compound, and an oxyphosphorus compound are further added and heated/fired in the presence of the grown titanium dioxide nucleus crystals. Thus, titanium dioxide is produced which comprises columnar particles having a weight-average major-axis length of 7.0-15.0 μm and in which particles having a major-axis length of 10 μm or longer account for 15 wt. % or more of all the particles.

A device for taking up a silicon melt comprises at least one block of a refractory with a capillary structure.

In one embodiment, a method for producing a naturally purified salt product such as magnesium sulfate heptahydrate, wherein the salt mixture is treated with a solution comprising magnesium chloride; the first slurry is separated to provide a second slurry, which is further separated to yield a first liquid stream; the first liquid stream is crystallized to provide the naturally purified salt product. In another embodiment, a high purity salt product is produced. In another embodiment, other products that are produced include naturally purified sodium chloride and magnesium chloride.

Provided is a method and an apparatus for purifying potassium nitrate from the solid waste produced by a chemical glass-strengthening process. In the method, the solid waste is melted into a liquid waste at first. Potassium nitrate of various purity grades can be obtained by batch processing the liquid waste through stepwise cooling processes of cooling the liquid waste to a first temperature facilitating the potassium nitrate contained in the liquid waste to be crystallized at a first rate and then cooling the liquid waste to a second temperature close to the freezing point of the potassium nitrate at a second rate that is slower than the first rate. The recovered potassium nitrate from the solid waste can be recycled and reused.

The invention provides a method of agglomeration (10) which has the steps of mixing a feedstock (12) of small particles which have an average particle size of 3 mm or less with a binder (14) which is in the form of a polyvinyl alcohol in the form of an aqueous polyvinyl alcohol solution in a first blender (16) to form a binder mixture (18), reacting a gelling agent (20) with the feedstock and the binder and processing the binder mixture to deliver an agglomerate (22).

A process is provided for preparing a salt product with reduced sodium content including the step of providing a concentrated brine, which is typically seawater, to which has been added potassium chloride. The mixture is transferred to a crystallizer unit where at least a portion of the mix is transferred to the crystallizer through a washing column. Liquid is evaporated from the crystallizer such that crystals form, crystals are passed from the crystallizer through said washing column to a separating unit such that in the passing through the washing column the crystals are rinsed with the brine portion being transferred as a counter current through the column. The inventive process is characterized by recycling of the brine from which the salt crystallizes, thus all main ingredients of the mixed input brine reach a steady equilibrium concentration in the mother liquor in the crystallizer. These will then precipitate as crystals, as more of the respective substances gets added to the mother liquor through inflow of mixed input brine. None of the liquor is purged out of the system as in conventional salt crystallizers. All the components in the feed are substantially contained in the product from the crystallizer either as crystalline material or soluble ingredients.

An object of the present invention is to provide a fine crystal particle production method and device that are excellent in mixing efficiency. This object is achieved by a method for producing fine crystal particles, comprising: a swirl flow producing step at which a swirl flow of liquid a comprising reactant A is supplied into a cylinder having a circumferential surface partially or wholly composed of a porous membrane; and a reaction step at which liquid b comprising reactant B which is reactive with the reactant A is supplied through the porous membrane to the swirl flow to effect mixing, whereby the reactants A and B are reacted to precipitate fine crystal particles.

Methods and apparatus for precipitating dissolved materials from a solution involve reduction of fines. In an embodiment, the method comprises: introducing a solution into a reactor, causing the dissolved materials in the solution to precipitate into crystals under a first reaction condition, adjusting the reaction condition from the first reaction condition to a second reaction condition, maintaining the reaction condition in the second reaction condition to cause a sub-population of the crystals to dissolve, and adjusting the reaction condition from the second reaction condition to the first reaction condition. In an embodiment, the apparatus comprises a reaction tank, a recycling path and at least an acid injector which is configured for dosing an acid into solution flow in the recycling path.

An application of carbon nanotubes on agglomerates of ore fines to increase the mechanical strength is provided. A process for the preparation of ore agglomerates having enhanced mechanical strength by the application of the carbon nanotubes is also provided.

The present invention provides a kiln for the combustion of agricultural waste. The kiln includes a central cylindrical combustion chamber. The central cylindrical combustion chamber includes a system for the control of combustion air to the combustion chamber. The kiln includes a second concentric cylinder surrounding the central cylindrical combustion chamber. The second concentric cylinder includes a system for the flow of cooling water through the first annulus between the central cylindrical combustion chamber and the second concentric cylinder. The kiln includes a system for the feeding of the agricultural waste into the central combustion chamber. The kiln includes a temperature sensing device to measure and display the temperature within the central combustion chamber during the combustion of the agricultural waste. The kiln includes a system for the recovery of ash from the kiln. In operation, the temperature of combustion is controlled to between 550° C. and 650° C. by a combination of increasing the supply of combustion air when the temperature in the central combustion chamber falls to near 550° C. and the introduction of cooling flowing water when the temperature in the central combustion chamber approaches 600° C.

The present invention relates generally to processes for preparing agglomerated particulate low-rank coal feedstocks of a particle size suitable for reaction in certain gasification reactors and, in particular, for coal gasification. The present invention also relates to integrated coal gasification processes including preparing and utilizing such agglomerated particulate low-rank coal feedstocks.

Small, little-known companies are selling CBD as a cure-all. While the Trump Administration has deregulated right and left — for instance, allowing polluters to go hog wild — the Food and Drug Administration isn't effing around when it comes to cracking down on companies selling supposed cures for the COVID-19 virus. Several of those targeted companies make CBD.…

For the safety of everyone, please do your part. Last Friday, health officers in Alameda and Contra Costa Counties and several of their Bay Area counterparts issued an order generally requiring workers and members of the public to wear face masks when they are out and about in the community. The orders were sweeping, and applied to most of the cases in which any of us leave our homes during this global health emergency.…

Conversely, greater infection rate suggests much lower fatality rate. A recent Stanford University study of COVID-19 infection in Santa Clara County suggests that the disease is vastly more widespread in the Bay Area than official data shows. Because the test was performed on volunteers rather than a randomized population, it is likely to have over-reported the rate of infection among its subjects.…