Air Pressure Measurements Research Articles

The Cultural Roots of Capitalism

The Cultural Roots of Capitalism Joyce Appleby (bio) In my Relentless Revolution I follow a few capitalist practices that flourished in the supportive environment of 17th-century England and became the key features of the dominant economic system of the 21st century. Why did it take so long for capitalism to emerge from the cocoon of tradition? In the 17th century the profitability of some English agricultural and manufacturing initiatives impressed contemporaries. At the same time, natural philosophers were proving the existence of a vacuum and measuring air pressure. None of this would have had any impact on the world of work where people and animals sweated in mine shafts and near blast furnaces had not the physical laws the naturalists studied lent themselves to devices for lifting, pushing, and rotating objects. Entrepreneurs then began adapting the steam engine, the pivotal innovation of the 18th century, to old ways of manufacturing and transporting. Click for larger view View full resolution William Hogarth’s The Industrious ‘Prentice Lord-Mayor of London, 1747. From Thomas Clerk, The Works of William Hogarth (London, 1821). With Newton’s physics came a diffused conviction that nature could be made to work for human beings; its forces could be understood and controlled. Enthusiasts wrote books simplifying the new science. They found a ready audience. In 18th-century England there was a vibrant intellectual scene, nourished by a plethora of civic organizations, self-improvement societies, bookstores, periodicals, pubs, and plays. A teenage Ben Franklin, visiting London to learn the mechanics of printing, discovered Newtonian physics, as did an ambitious exciseman named Thomas Paine. About the same time, Voltaire, destined to be the signature philosopher of the Enlightenment, spent three years there and pronounced Newton’s theory a human triumph. Once capitalism’s amazing power to generate wealth was detected, most countries—at least in the West—wanted part of the action. And it was relatively easy for other countries to copy English innovations; the copiers didn’t have to replicate the complex of propitious factors necessary for capitalism to install itself the first time. They could also discriminate between what they wished to copy and what they found distasteful in the modernizing dynamic of capitalism. Western Europeans began revising their cultural forms, taking up new tastes, and talking with a fresh vocabulary about the impact of private enterprise on the welfare of the society as a whole. In time, traditional ways of acting and thinking lost their controlling power. The value systems of the past came from a world of scarcity. Traditions ennobled values compatible with restraint. Capitalism undermined that system and launched a culture of its own based on rising expectations and liberal morals. More properly, it launched diverse cultures as each country created its own mix of innovation and tradition. By the end of the 19th century, it was the United States and Germany that were nurturing the cutting-edge innovations in chemistry and electricity. Constant innovations didn’t come without cost, because every improved device rendered obsolete its predecessor. Prodded by the lure of stronger sales and higher profits, innovators hurt established industries. The 20th-century Austrian economist Joseph Schumpeter captured the essence of capitalism in the phrase “creative destruction” of the old by the new. Rarely has anyone so precisely hit the nail on the head. Innovation fueled the relentless revolutions of capitalism, revealing its most striking feature to be its inextricable connection with change—the constant disturbance of once stable material and cultural forms. While it destroyed venerable institutions and settled communities, capitalism also opened up to a significant proportion of men and women in the West the possibility of organizing their energy, attention, and talents in order to forge new trade links and meet old needs with new commercial products. There were more failures than successes, and the successes brought unintended consequences. Turbulence was written into the system, but capitalism had already become self-sustaining before anyone pointed this out. Capitalism was never just an economic system. [End Page 9] Its focus on enhancing production through private initiatives impinged on every facet of life and was itself affected by every institution that shaped its participants. Where commerce could live within the...

Scale modeling studies on stack effect in tall vertical shafts

Natural ventilation was provided by tall vertical shafts such as solar chimney while designing some green buildings. For buildings with a tall vertical shaft located in very cold countries, measured pressure difference due to stack effect was up to 300 Pa. Air motion induced by stack effect would give adequate ventilation flow rate. However, stack effect would also give adverse effect if not utilized properly in this green design. Smoke would spread faster to other parts of the building in an accidental fire. Therefore, estimations of stack pressure by simple hydrostatic equation used to be criticized in performance-based design. Further studies are required and will be justified by scale model experiments in this article. Stack effect in a vertical shaft was studied experimentally by a model shaft of size 0.05 × 0.05 m2 and height 2.0 m. Air temperature inside the model was kept at constant values above outdoor by wounding hot electric wires. Vertical air temperature profiles inside and outside of the model at different heights were measured. Measured air pressure difference profiles between indoor and outdoor were then compared with those estimated from the air temperature difference. Results were then applied to justify stack pressure estimations by the hydrostatic models. From this study, hydrostatic equations are confirmed to be acceptable for studying stack pressure in tall vertical shafts.

Evaluation of an Air Pressure–Based Proxy for Storm Activity

Abstract Yearly percentiles of geostrophic wind speeds serve as a widely used proxy for assessing past storm activity. Here, daily geostrophic wind speeds are derived from a geographical triangle of surface air pressure measurements and are used to build yearly frequency distributions. It is commonly believed, however unproven, that the variation of the statistics of strong geostrophic wind speeds describes the variation of statistics of ground-level wind speeds. This study evaluates this approach by examining the correlation between specific annual (seasonal) percentiles of geostrophic and of area-maximum surface wind speeds to determine whether the two distributions are linearly linked in general. The analyses rely on bootstrap and binomial hypothesis testing as well as on analysis of variance. Such investigations require long, homogeneous, and physically consistent data. Because such data are barely existent, regional climate model–generated wind and surface air pressure fields in a fine spatial and temporal resolution are used. The chosen regional climate model is the spectrally nudged and NCEP-driven regional model (REMO) that covers Europe and the North Atlantic. Required distributions are determined from diagnostic 10-m and geostrophic wind speed, which is calculated from model air pressure at sea level. Obtained results show that the variation of strong geostrophic wind speed statistics describes the variation of ground-level wind speed statistics. Annual and seasonal quantiles of geostrophic wind speed and ground-level wind speed are positively linearly related. The influence of low-pass filtering is also considered and found to decrease the quality of the linear link. Moreover, several factors are examined that affect the description of storminess through geostrophic wind speed statistics. Geostrophic wind from sea triangles reflects storm activity better than geostrophic wind from land triangles. Smaller triangles lead to a better description of storminess than bigger triangles.

Pressure-sensitive blackbody point radiation induced by infrared diode laser irradiation

Ultrabroadband radiation from Yb(2)O(3) at ambient and low air pressures was investigated under the excitation of a 980 nm diode laser. The radiation was confirmed to be blackbody radiation, and it is sensitive to environmental air pressure in the way that the integrated radiation intensity decreases linearly with increasing air pressure. An ideal gas model may be employed to interpret the linear dependence. The pressure-sensitive radiation characteristic provides a potential method for noncontact measurement of air pressure with high accuracy.

An Improved Air Pressure Measuring Method and Demonstrated Application to Drainage in Heterogeneous Soils

Water flow in the vadose zone is often modeled as a single‐phase flow where the air phase is assumed to be free to flow. Although this is a fair assumption in many practical cases, there are a number of applications where the free flow of air is hindered due to various causes. Air phase that is not free to flow in the subsurface can lead to a decreased infiltration rate or changes in water flow paths. In this study, we improved methods for measuring air pressure in wet soil, and demonstrated its applicability to investigate how the air phase can play a critical role in heterogeneous soil under certain conditions. To achieve this, we performed two sets of experiments. In the first set of experiments, we tested seven different porous material–hydrophobic treatment combinations for air pressure measurement in soils that were initially water saturated. In the second set of the experiment, drainage was induced in a layered column where a layer of coarse sand was overlaid by finer sand. Air pressure was monitored using the method selected based on the results of the first experiment. As the drainage proceeded, the layer of coarse sand released water when the air phase penetrated through the fine sand layer. The air pressure in the coarse layer rapidly decreased (became negative) as the water was released. The results demonstrated that the improved air pressure measuring method successfully indicated a decrease in air pressure during the drainage, and that the single‐phase approach where only the water pressure is considered becomes invalid for cases where free air flow is hindered and water–air interaction is significant.

Anomaly Detection in Environmental Monitoring Networks [Application Notes

We apply a recently developed model for anomaly detection to sensor data collected from a single node in the Heron Island wireless sensor network, which in turn is part of the Great Barrier Reef Ocean Observation System. The collection period spanned six hours each day from February 21 to March 22, 2009. Cyclone Hamish occurred on March 9, 2009, roughly in the middle of the collection period. Our system converts sensor measurements to elliptical summaries. Then a dissimilarity image of the data is built from a measure of focal distance between pairs of ellipses. Dark blocks along the diagonal of the image suggest clusters of ellipses. Finally, the single linkage algorithm extracts clusters from the dissimilarity data. We illustrate the model with three two-dimensional subsets of the three dimensional measurements of (air) pressure, temperature and humidity. Our examples show that iVAT images of focal distance are a reliable basis for estimating cluster structures in sets of ellipses, and that single linkage can successfully extract the indicated clusters. In particular, we are able to clearly isolate the cyclone Hamish event with this method, which demonstrates the ability of our model to detect anomalies in environmental monitoring networks.

Experimental Investigation on Reciprocating Air Compressor Performance

This study presents an accurate measurement method for measuring air pressure and temperature of air compressor when a reciprocating gas compressor performance. The design and main functions of the automatic acquisition and testing system for air compressor performance was introduced. The system has the advantages of excellent practicability, rapidity, stability, reliability, operability and good security feature. The system can give real-time process monitoring on test data and compile test reports of the reciprocating two stages compressor. The system can display, save and print performance curve, respectively.

Mathematical Modeling of Lake Tap Flows

A lake tap is the submerged piercing of a tunnel at the intake to connect the reservoir to the tunnel system. It is referred to as a dry lake tap if the tunnel is dry before the blasting of the last rock plug at the tunnel entrance. Transient state conditions in the tunnel following a dry lake tap are modeled using the lumped and distributed-system approaches. Fourth-order Runge-Kutta method and the method of characteristics are used in the lumped-system model and distributed-system models, respectively. The results computed by the lumped and distributed-system approaches agree with one another. Pressures computed by using distributed-system and lumped-system models are compared with the experimental results available in literature for rapid filling of a pipeline with closed end. The rate of dissipation of pressure oscillations in the measured air pressure during prototype lake tap at Crater Lake Snettisham project in Alaska, and in the experiments reported in the literature is higher than that computed by the mathematical models using steady state friction and constant wave velocity.

Short‐term variations in wind power: Some quantile‐type models for probabilistic forecasting

AbstractWe discuss some ways of formulating quantile‐type models for forecasting variations in wind power in the short term (within a few hours). Such models predict quantiles of the conditional distribution of the wind power available at some future time using information presently available. A natural reference for models of this kind is a ‘probabilistic‐persistence’ quantile forecast whose only input is the present wind power. Using data from some New Zealand wind farms, we find that more complex quantile models can readily improve on probabilistic persistence in resolution but not in sharpness. The most valuable model inputs, apart from the present power, are found to be real‐time air pressure measurements and a power total‐variation indicator. Copyright © 2010 John Wiley & Sons, Ltd.

Oxygen and Carbon Dioxide Distribution And Movement in Passively Aerated Compost Piles

Distributions of O2 and CO2 concentrations across a cross section of a full-scale passively aerated, mechanically turned, compost piles were measured as a function of time over an 11 day long period covering two pile turnings. The compost pile had a triangular cross section, was 1.8 m high, 4.4 m wide, 80 m long and consisted of sewage sludge, yard/park waste and screening residue from previously composted materials. The measurements were conducted in one cross section of the pile. The O2 and CO2 concentration measurements were used in combination with earlier published measurements of air permeability and air pressure inside the compost pile to calculate O2 and CO2 fluxes across the pile surface as functions of time and location as well as estimation of total specific oxygen consumption rates in the compost. Distributions of O2 and CO2 concentrations inside the pile were relatively constant with time and exhibited high O2 concentrations near the surface and high CO2 concentrations near the center of the pile. Maximum O2 fluxes in the compost occurred along the lower edges of the pile and equalled up to 15 kg/m−2 h−1 while maximum CO2 fluxes occurred at the center top of the pile and equalled up to 700 g m−2 h−1. Average daily CO2 emissions from the compost were up to 3.4 kg m3 d−1 while the corresponding O2 flux into the compost pile was up to 53 kg m3 d−1. Average O2 consumption was 1.4 kg m−3 d−1 while average CO2 production was 1.5 kg m−3 d−1 at the measurement location over the 11 day experimental period.

Note: A robust low-cost high-sensitivity subangstrom bidirectional displacement sensor

The design of a simple, robust, low-cost, and bidirectional displacement sensor with subangstrom resolution is described. A small gold plate is attached to the object, whose displacement is to be measured, and a small gold tip is brought into contact with the plate, establishing a reference current between the two. Movements of the gold plate away from the tip lead to a change in the tip-plate current; the reference current is then re-established by moving the tip using a simple magnetic actuator. The resolution of the sensor has been calibrated using an interferometer and was shown to be as high as 0.3 Å per system count. Potential applications of the sensor are numerous, including microbar air pressure measurement, motion and infrasound detection, thermal sensing, and gravitational field and relativistic gravity wave measurement.

Air mass balance for mass flow rate calculation in pneumatic conveying

Mass flow rate of solids is probably the most important parameter in pneumatic conveying systems. It is a challenging task to measure this parameter in gas–solid flows. A new and simple model is presented and described to calculate the mass flow rate of solids in pneumatic conveying systems, based on air flow and pressure measurements. The principle of the model is conservation of mass, and it is applied in a horizontal straight pipe section. Two tests need to be performed on the actual conveying rig to be used for calibration of the model. Due to the kind of sensors used to carry out the necessary measurements, application of the model is rather inexpensive and non-intrusive. The model has been validated successfully with data from two different single blow tank conveying systems and in dense and dilute phase conveying. Four test materials were used for validation of the model: alumina, baryte, cement and dextrose. Provided that the requirements to apply the air mass balance model are fulfilled, its effective widespread application on real industrial systems seems plausible.

Measuring air pressure with a polymeric gas sensor

In this communication we describe the application of a conductive polymer gas sensor as an air pressure sensor. The device consists of a thin doped poly(4'-hexyloxy-2,5-biphenylene ethylene) (PHBPE) film deposited on an interdigitated metallic electrode. The sensor is cheap, easy to fabricate, lasts for several months, and is suitable for measuring air pressures in the range between 100 and 700 mmHg.

Potential flow models of suspension current air pressure

AbstractWe present, analyse and discuss air-pressure data from finite-volume chute flows of dry fine snow in air. These experiments have the correct similarity criteria to model powder-snow avalanches and demonstrate the transition from a dense to a suspended flow. We measured the dynamic air pressure at the base of the flow, which features a marked negative pressure peak immediately behind the front. This feature is also seen in observations of natural powder-snow avalanches measured in Russia, Japan and Switzerland in direct numerical simulations of non-Boussinesq suspension flows and in ping-pong ball avalanches. This is evidence for large internal motions and suggests that there is a coherent vortex in the avalanche front. This can result in impact pressures many times larger than those expected from the mean flow velocity. We analyse the external air pressures using three models and show how the geometry and velocity of the flow can be found from this single air-pressure measurement. We also measured flow heights and speeds using image analysis and show that the speed is roughly independent of the slope angle and scales with the release size raised to the power 1/4, as predicted by similarity analysis for pseudo two-dimensional (2-D) flows.

Development of a measurement platformon a light airplane and analysis of airborne measurementsin the atmospheric boundary layer

In the present paper we provide an overview of a long term research project aimed at setting up a suitable platform for measurements in the atmospheric boundary layer on a light airplane along with some preliminary results obtained from fi eld campaigns at selected sites. Measurements of air pressure, temperature and relative humidity have been performed in various Alpine valleys up to a height of about 2500 m a.m.s.l. By means of GPS resources and specifi c post-processing procedures careful positioning of measurement points within the explored domain has been achieved. The analysis of collected data allowed detailed investigation of atmospheric vertical structures and dynamics typical of valley environment, such as morning transition from ground based inversion to fully developed well mixed convective boundary layer. Based on data collected along fl ights, 3D fi elds of the explored variables have been detected and identifi ed through application of geostatistical techniques (Kriging). The adopted procedures allowed evaluation of the intrinsic statistical structure of the spatial distribution of measured quantities and the estimate of the values of the same variable at unexplored locations by suitable weighted average of data recorded at close locations. Results thus obtained are presented and discussed.

Validating global hydrological models by ground and space gravimetry

The long-term continuous gravity observations obtained by the superconducting gravimeters (SG) at seven globally-distributed stations are comprehensively analyzed. After removing the signals related to the Earth’s tides and variations in the Earth’s rotation, the gravity residuals are used to describe the seasonal fluctuations in gravity field. Meanwhile, the gravity changes due to the air pressure loading are theoretically modeled from the measurements of the local air pressure, and those due to land water and nontidal ocean loading are also calculated according to the corresponding numerical models. The numerical results show that the gravity changes due to both the air pressure and land water loading are as large as 100×10−9 m s−2 in magnitude, and about 10×10−9 m s−2 for those due to the nontidal ocean loading in the coastal area. On the other hand, the monthly-averaged gravity variations over the area surrounding the stations are derived from the spherical harmonic coefficients of the GRACE-recovered gravity fields, by using Gaussian smoothing technique in which the radius is set to be 600 km. Compared the land water induced gravity variations, the SG observations after removal of tides, polar motion effects, air pressure and nontidal ocean loading effects and the GRACE-derived gravity variations with each other, it is inferred that both the ground- and space-based gravity observations can effectively detect the seasonal gravity variations with a magnitude of 100×10−9 m s−2 induced by the land water loading. This implies that high precision gravimetry is an effective technique to validate the reliabilities of the hydrological models.

Real-time procedure for detection of a meteotsunami within an early tsunami warning system

A meteotsunami detection algorithm, based on real-time measurements of air pressure, was developed and tested. The algorithm consists of two modules: the first module detects potentially dangerous air pressure disturbances with tendencies exceeding a certain threshold value; the second module determines the speed and direction of propagation of those disturbances. The algorithm was tested on artificial and measured air pressure time series from three Mediterranean meteotsunami hot-spots (the Balearic Islands, the northern Adriatic, the middle Adriatic). Functionality, rapidity and reliability of two methods for determination of the air pressure disturbance’s propagation speed and direction, the isochronal analysis method and the pressure tendency method, were tested. Both methods work acceptably well, and the detection algorithm is generally able to detect potentially dangerous air pressure disturbances and to determine their speed and direction of propagation.

High precision pressure measurement with a funnel

A simple experimental device for high precision differential pressure measurements is presented. Its working mechanism recalls that of a hydraulic press, where pressure is supplied by insufflating air under a funnel. As an application, we measure air pressure inside a soap bubble. The soap bubble is inflated and connected to a funnel which is placed, upside down, in a container filled with distilled water, placed on a scale. Our method provides a theoretical precision for the pressure measurement of the order of 0.01 Pa. Beyond this, the advantage of this method relies on the simplicity of the materials used and on the opportunity to discuss, at an undergraduate level, basic concepts regarding all those phenomena in which low or very low differential pressures are relevant.

Stochastic inversion of pneumatic cross-hole tests and barometric pressure fluctuations in heterogeneous unsaturated formations

The distributions of permeability and porosity are key factors that control airflow and gas phase transport in unsaturated formations. To understand the behavior of flow and transport in such formations, characterization procedure is a typical approach that has been widely applied to laboratories and fields. As is recognized by most investigations, this approach relies on accurate measurements, and more importantly, an adequate tool to interpret those measurements from experiments. This study presents a pneumatic inverse model that is capable to estimate the distributions of permeability ( k) and porosity ( ϕ) with high resolution in heterogeneous unsaturated formations. Based on the concept of sequential successive linear estimator (SSLE), the developed model accounts for compressibility and density of air and estimates the geologic parameters using air pressure measurements from sequential cross-hole pneumatic pumping or injection tests. Four synthetic examples, including a one-dimensional well-posed, a horizontally two-dimensional, and two three-dimensional problems, are used to evaluate the developed model in estimating the distributions of permeability and porosity in unsaturated formations. Results of the numerical experiments are promising. The developed pneumatic inverse model can reconstruct the property (i.e., permeability and porosity) fields if the well-defined conditions are met. With a relatively small number of available measurements, the proposed model can accurately capture the patterns and the magnitudes of estimated properties for unsaturated formations. Results of two complex three-dimensional examples show that the proposed model can map the fracture connectivity using a small number of subsurface pressure measurements and estimate k and ϕ in shallow soil layers using spatial variations of barometric pressure.

Pneumatic frequency selection filter in the prior stage of the air pressure transducer

To use frequency selection filter with electrical components, the signal from the transducer should have the detailed information with enough signal-to-noise ratio. In the measurement of air pressure, if the small variation is added to the big amplitude of slowly varying signal, there needs to eliminate the low frequency component in front of the transducer to avoid saturation. To achieve that, the concept of balancing tube was suggested and analyzed as pneumatic high pass filter. The simple method to adjust and find the cutoff frequency of the high pass filter is shown and validated. One application of this measurement technique in physiological monitoring using air mattress and balancing tube is summarized.