Academic literature on the topic 'Total pressure and total temperature measurement'

The aspirating probe originally designed by Epstein and Ng at MIT was modified by replacing the two platinum-coated tungsten hot wires normally used with platinum–iridium alloy wires. The resulting improved unsteady total pressure and total temperature resolution of the modified probe is demonstrated. Flowfield measurements were made downstream of NASA Rotor 37 for a part-speed operating condition to test the performance of the probe. Time-resolved blade-to-blade total temperature and total pressure as calculated from the two platinum–iridium hot-wire voltages are shown. The flowfield measurements are compared with independent measurements of total pressure with high response transducers and total temperature calculated from laser anemometer measurements. Limitations of a more often used unsteady temperature data reduction method, which involves only one aspirating probe hot-wire voltage and a high-response pressure measurement, are discussed.

An experimental technique for the measurement of flow total temperature in a turbine facility is demonstrated. Two thin film heat transfer gases located at the stagnation point of fused quartz substrates are operated at different temperatures in order to determine the flow total temperature. With this technique, no assumptions regarding the magnitude of the convective heat transfer coefficient are made. Thus, the probe can operate successfully in unsteady compressible flows of arbitrary composition and high free-stream turbulence levels without a heat transfer law calibration. The operation of the total temperature probe is first demonstrated using a small wind tunnel facility. Based on results from the small wind tunnel tests, it appears that the probe total temperature measurements are accurate to within ±1 K. Experiments using the probe downstream of a high-pressure turbine stage are than described. Both high and low-frequency components of the flow total temperature can be accurately resolved with the present technique. The probe measures a time-averaged flow total temperature that is in good agreement with thermocouple measurements made downstream of the rotor. Frequencies as high as 182 kHz have been detected in the spectral analysis of the heat flux signals from the total probe. Through comparison with fast-response aerodynamic probe measurements, it is demonstrated that the current measurement location, the total temperature fluctuations arise mainly due to the isentropic extraction of work by the turbine. The present total temperature probe is demonstrated to be an accurate, robust, fast-response device that is suitable for operation in a turbomachinery environment.

The measurement of unsteady pressures within the hot components of gas turbine engines still remains a true challenge for test engineers. Several high-temperature pressure sensors have been developed, but so far, their applications are restricted to unsteady wall static pressure measurements. Because of the severe flow conditions such as turbine inlet temperatures of 1700 °C and pressures of 50 bar or more in the most advanced aero-engine designs, few (if any) experimental techniques exist to measure the time-resolved flow total pressure inside the gas path. This article describes the measurements performed at the turbine exit of a military engine with a cooled fast response total pressure probe. The probe concept is based on the use of a conventional miniature piezo-resistive pressure sensor, located in the probe tip to achieve a bandwidth of at least 40 kHz. Due to the extremely harsh conditions, the probe and sensor are heavily water cooled. The probe was designed to be continuously immersed into the hot gas stream to obtain time series of pressure with a high bandwidth and therefore statistically representative average fluctuations at the blade passing frequency (BPV). The experimental results obtained with a second-generation prototype are presented. The probe was immersed into the engine through the bypass duct between turbine exit and flame-holders of the afterburner of a Volvo RM12 engine, at exhaust temperatures above 900 °C. The probe was able to resolve the BPV (∼17 kHz) and several harmonics up to 100 kHz.

In this paper, the measurement accuracy of two different types of total pressure probe and total temperature probe in turboshaft engine compressor inlet channel and the influence of these two probes on the flow field through numerical simulation was studied. At the same time, the influence of the probe structure and installation position on probe measurement results under three typical working conditions of cruise, maximum continuous and takeoff was analyzed. The simulation results showed that the higher the engine inlet flow rate, the greater the measurement error of the probe. Comparing with the total temperature probe, the total pressure probe measurement accuracy is more influenced by the flow rate. The velocity uniformity is less affected by the engine operating conditions and is mainly related to the structure of the inserted probes. The closer the total pressure probe to the support plate, the greater the measurement error. The probe installation position has a small effect on the total pressure loss coefficient at the outlet.

Abstract. In the first study reported on here, requirements on random uncertainty of instantaneous temperature measurements, sampling frequency, season and pressure, required to ensure a minimum random uncertainty of monthly mean temperatures, have been explored. These results then inform analyses conducted in a second study which seeks to identify the optimal location of sites for detecting projected trends in upper-air temperatures in the shortest possible time. The third part of the paper presents a similar analysis for the optimal locations of sites to detect projected trends in total column ozone. Results from the first study show that only for individual measurement random uncertainties > 0.2 K does the measurement random uncertainty start to contribute significantly to the random uncertainty of the monthly mean. Analysis of the effects of the individual measurement random uncertainty and sampling strategy on the ability to detect upper-air temperature trends shows that only when the measurement random uncertainty exceeds 2 K, and measurements are made just once or twice a month, is the quality of the trend determination compromised. The time to detect a trend in some upper-air climate variable is a function of the unforced variance in the signal, the degree of autocorrelation, and the expected magnitude of the trend. For middle tropospheric and lower stratospheric temperatures, the first two quantities were derived from Microwave Sounding Unit (MSU) and Advanced Microwave Sounding Unit (AMSU) measurements while projected trends were obtained by averaging 21st century trends from simulations made by 11 chemistry–climate models (CCMs). For total column ozone, variance and autocorrelation were derived from the Bodeker Scientific total column ozone database with projected trends obtained from median values from 21 CCM simulations of total column ozone changes over the 21st century. While the optimal sites identified in this analysis for detecting temperature and total column ozone trends in the shortest time possible result from our use of only one of a wide range of objective strategies, these results provide additional incentives for initiating measurement programmes at these sites or, if already in operation, to continue to be supported.

ABSTRACT Laboratory tests for technical evaluation or irrigation material testing involve the measurement of many variables, as well as monitoring and control of test conditions. This study, carried out in 2016, aimed at using statistical quality control techniques to evaluate results of dripper tests. Exponentially weighted moving average control charts were elaborated, besides capability indices for the measurement of the test pressure and water temperature; and study on repeatability and reproducibility (Gage RR) of flow measurement system using 10 replicates, in three work shifts (morning, afternoon and evening), with 25 emitters. Both the test pressure and water temperature remained stable, with “excellent” performance for the pressure adjustment process by integrative-derivative proportional controller. The variability between emitters was the component with highest contribution to the total variance of the flow measurements, with 96.77% of the total variance due to the variability between parts. The measurement system was classified as “acceptable” or “approved” by the Gage RR study; and non-random causes of significant variability were not identified in the routine of tests.

Summary Alkalinity is needed in many water-treatment calculations such as scale, corrosion, precipitation, and oxidation, yet the concept is often misunderstood. In natural waters, alkalinity often is not equal to bicarbonate concentration, because natural waters contain base-contributing anions that can significantly affect alkalinity. However, alkalinity is commonly assumed to be equal to the bicarbonate concentration in many scale- and corrosion-prediction algorithms. When other anions (e.g., carboxylates) are present, bicarbonate concentration in production tubing is not a conservative quantity; it varies with CO2 partial pressure, temperature, and carboxylate concentrations in a complicated manner up and down a well. Reliable methods to accurately measure true alkalinity are scarce, especially when multiple weak acids are present and the effects of TDS on electrode and color endpoint are significant. Oilfield brines contain aliphatic carboxylic acids of one to six carbons (e.g., acetate) up to 5000 mg/L. The highest concentrations of carboxylates tend to be in waters from reservoirs at temperatures of 80 to 100°C. In this paper, a new analytical procedure and computation routine to determine alkalinity and carboxylic acids simultaneously will be discussed. The procedure was recently debugged and simplified by the Rice U. Brine Chemistry Consortium (Rice BCC). The new titration method is based upon simultaneous analysis of the titration curve determined at fixed PCO2 and emphasizes the titration shape (profile) instead of the endpoint inflection as is done presently. A wide range of natural and synthetic waters has been tested. Excellent agreement was observed between the true and calculated carboxylic acid concentration with a correlation coefficient squared of 0.9986. Once the total alkalinity and acetic acid concentrations are determined, the theoretically correct bicarbonate concentration and/or pH at any given operation temperature or pressure can be calculated. The intricate interrelationship of total alkalinity, carboxylic acids, and pH on scale and corrosion will be discussed by using case studies.

This paper presents the results of two test programmes using novel instrumentation to characterise the pressure and turbulent velocity fields in gas-turbine combustor exit flows. The probes are uncooled, therefore a fast-insertion traverse system is employed to prevent thermal degradation of the instrumentation in these severely hostile high-temperature environments. High-bandwidth ultra-miniature pressure transducers are used to measure unsteady total pressure, whilst a Pitot tube is employed to measure time-averaged total pressure. The probes are 4 mm in diameter with a measurement bandwidth of the order of 100 kHz. In the first test programme, the probes are used to characterise the streamwise turbulent velocity field approximately two axial chords downstream of an uncooled single-stage turbine in a turbojet engine. Established data reduction methods and calibration against a hot-wire are used to obtain turbulent velocity fluctuations from unsteady total pressure measurements. Comprehensive turbulence results are presented including time-histories, power spectra, intensities, and lengthscales obtained at four-engine conditions and at two radial and two circumferential measurement locations. In the second test programme the probes are demonstrated in an industrial combustor rig, featuring a can combustor with swirler nozzle and no dilution holes, at temperatures up to 1500 K. Static pressure fluctuations are obtained up to 100 kHz, and some typical combustor spectral features are identified.

This thesis work was performed as a collaboration between the Royal Institute of Technology in Stockholm and Siemens Industrial Turbomachinery in Finspång. It was undertaken with the purpose of investigating the use of CFD methods in ANSYS CFX to predict flow mixing in gas turbines. The results were evaluated against experimental data gathered as part of an international collaboration; The FACTOR project. The experimental data investigated were total temperature and total pressure at nozzle guide vane inlet and outlet. The results thus focus mainly on nozzle guide vane inlet and outlet due to the nature of the available experimental data. The distribution of these parameters was also investigated in the NGV flow channel and on the vane surface, but it is appreciated that any conclusions drawn from these results are speculative in nature due to the lack of experimental data. Any conclusions drawn must be placed in perspective of the evaluation of NGV inlet and outlet, for which experimental data is available. The focus was on the mixing of the total temperature and total pressure in a nozzle guide vane connected to a combustion chamber simulator. The methods investigated were RANS-SST, SBES and LES-WALE. The main conclusions are that the inclusion of a combustion chamber mesh and thus simulating the CC flow increases the accuracy of the nozzle guide vane results for RANS-SST simulations. It is also observed that in general the SBES and LES-WALE method yield highly similar results under the investigated circumstances, and that both these methods show a general improvement over the RANS-SST method.
Detta examensarbete utfördes som ett samarbete mellan KTH i stockholm och Siemen Industrial Turbomachinery i Finspång. Det undertogs med syftet att undersöka användning av CFD-metoder i ANSYS CFX för att förutspå flödesmixning i gasturbiner. Resultaten utvärderades mot experimentel data som samlats genom ett internationellt samarbete: FACTORprojektet. Den experimentella data som undersökts var totaltemperatur och totaltryck vid in- och utloppet till ett statorblad. Resultaten fokuserar huvudsakligen vid in- och utlopp till statorbladed på grund av den tillgängliga experimentella datan. Distributionen av totaltemperatur och totaltryck mellan dessa plan undersöktes också, men det måste lyftas att alla slutsatser som dras av dessa resultat är till någon grad spekulativ på grund av tillgängliga datans natur. Alla slutsatser som dras härutav måste utvärderas i samband med den tillgängliga datan. Det huvudsakliga focuser låg vid mixningen av totaltemperature och totaltryck i ett statorbland anslutet till en brännkammarsimulator. De undersöka metoderna var RANS-SST, SBES och LES-WALE. De huvudsakliga slutsatserna är att inkluderandet av en brännkammar-mesh och därmed simuleringen av brännkammarflödet förbättrar kvaliten på resultatet för statorbladen för RANS-SST simuleringar. Det har också framkommit att SBES och LES-WALE-metoderna resulterar i högst likvärda resultat i de undersökta omständigheterna, och att båda dessa metoder ger ett generellt förbättrat resultat vid jämförelse med RANSSST.

This thesis presents the use of an unsteady total pressure measurement to detect laminar-to-turbulent transition. A miniature dynamic pressure transducer, Kulite model XCS-062-5D, was utilized to measure the total pressure fluctuations, and was integrated with an autonomous boundary layer measurement device that can withstand flight test conditions. Various sensor-probe configurations of the Kulite pressure transducer were first examined in a wind tunnel with a 0.610 m (2.0 ft) square test section with a maximum operational velocity of 49.2 m/s (110 mph), corresponding dynamic pressure of 1.44 kPa (30 psf). The Kulite sensor was placed on an elliptical nose flat plate where the flow was known to be turbulent. The Kulite sensor was then evaluated to measure total pressure fluctuations in laminar, turbulent, and transition of boundary layers developed on the flat plate in the same wind tunnel. The root-mean-square value of total pressure fluctuations was less than 1 % of the local free-stream dynamic pressure in the laminar boundary layer, but was about 2 % in the turbulent boundary layer. The value increased to 4 % in transition, indicating that the total pressure fluctuation measurements can be used not only to distinguish the laminar boundary layer from the turbulent boundary layer, but also to identify the transition region. The unsteady total pressure measurement was also conducted in a with a 2.13 m (7.0 ft) by 3.05 m (10.0 ft) section with similar operational velocity range as the previous wind tunnel. The Kulite sensor was placed on a wing model under laminar and transition conditions. The testing yielded similar results, demonstrating the usefulness of total pressure measurement for identifying the laminar-to-turbulent transition.

Distortion tolerant fans represent the enabling technology for the successful implementation of highly integrated airframe propulsion system vehicles. This investigation extends the study of fan-distortion interactions to an actual turbofan engine with a total pressure distortion profile representative of a boundary-layer ingesting (BLI) embedded engine. The goal was to make a series of flow measurements that contribute to the overall physical understanding of this complex flow situation. Proper uncertainty analysis is critical to extracting meaning from the data measured in this study. The important information in the measurements is contained in small differences that lead to large impacts on the fan performance. In some cases, these differences were measured to a useful degree of accuracy, while in others they were not. One important application of the uncertainty analysis techniques developed in this work is the identification of the dominant error sources that resulted in unacceptable uncertainties. This dissertation presents an experimental study of transonic fan response to inlet total pressure distortion. A Pratt and Whitney JT15D-1 turbofan engine was subjected to a total pressure distortion representative of a boundary layer ingesting serpentine inlet. A 5-hole probe measured the aerodynamic response of the fan rotor in terms of flow angles, total pressure, and static pressure. A thermocouple embedded in the probe measured the rotor outlet total temperature. These measurements enabled the full characterization of the flow condition at each measurement point. The results indicate that a trailing edge separation and reattachment cycle experienced by the blades caused variations in the work input to the flow and resulted in a non-uniform rotor outlet flow profile. The details of the aerodynamic process and several means for improving distortion response are presented in this context. As a second theme, the modern measurement and uncertainty analysis techniques required to obtain useful information in this situation are developed and explored. Uncertainty analysis is often treated as a less glamorous afterthought in experimental research. However, as technology develops along lines of ever increasing system-level integration, simply suggesting the solution to a single flow situation does not repre- sent closure to the larger problem. In addition to frameworks for developing distortion tolerant fans, frameworks for developing frameworks are required. Uncertainty-drivenexperimental techniques represent the enabling methodology for the discovery and un- derstanding of the subtle phenomena associated with such coupled performance. These considerations are required to extend the usefulness of the results to the overarching issue of integrating the complex performance of individual components into an overall superior system. The experimental methods and uncertainty analysis developed in this study are presented in this context.
Ph. D.

A non-invasive, in vitro method of estimating mean pulmonary artery pressure (PAP) was developed. This information was obtained by establishing a relationship between the pneumatic right drive pressure (RDP) and PAP waveforms. The RDP-PAP relationship was formalized into a series of multiple-linear regression equations for TAH cardiac cycles of known fill volume (FV). Correlation of computed estimates of PAP to actual measurements showed that these equations were greater than 92% accurate within 1.84 mmHg. In addition, while the RDP-PAP relationships were wholly dependent on FV, it was shown that they are independent of the manner in which FV was obtained. This method proved useful over the clinical operating range of the pneumatic heart driver, as well as over the normal physiological range of PAP in the human. Effectiveness of this method in vivo needs to be demonstrated.

High blood pressure (BP) is the most significant risk factor for cardiovascular disease and a major contributor to chronic disease burden in the United States. Chronic conditions are the most common reason for office-based physician visits among adults, accounting for 37% of all visits. Home BP monitoring when combined with clinical support may help engagement with care and improve condition control. This study examines the extent to which home BP measurement is associated with total office visits among Medicare beneficiaries with self-reported high BP and the influence by other related factors. The 2018 Medicare Current Beneficiary Survey (MCBS) was used in the study. The study population consists of Medicare beneficiaries (n=4,456) with self-reported high BP who had at least one total office visit in the year. Total office visits served as the outcome and were dichotomized to low (1-5 visits) and high (greater than 5 visits), while self-reported home BP measurement was the primary independent variable. Andersen’s conceptual framework was used to establish the co-variates [Predisposing factors: age, gender, race, education; Enabling factors: insurance plan (Medicare Advantage, MA), income, patients’ satisfaction (a. quality, b. information); Individual needs: smoking, BMI; Environment: region]. Bivariate analysis using a chi-square test for independence, unadjusted and adjusted logistic regression was conducted using SAS v 9.4. Of the study population, 57.9% reported measuring blood pressure at home. Approximately 95.6% and 94.2% of beneficiaries were satisfied with the quality of care received and information about their symptoms respectively. Bivariate analysis showed a significant relationship between total office visits and home BP measurement (p<0.05). Unadjusted logistic regression results noted that those who reported home BP measurement had increased odds of high total office visits [uOR: 1.17 (1.02-1.33)]. This relationship was slightly increased in the adjusted analysis when accounting for other factors of interest [aOR:1.22 (1.06- 1.40)]. Those aged 65-74 years had reduced odds [aOR: 0.77 (0.61 -0.98)], females had increased odds [aOR: 1.38 (1.19 – 1.61)], and those with higher education had increased odds [aOR: 1.41 (1.14 -1.75)] of high total office visits. Those not enrolled in MA [aOR: 3.37 (2.31- 4.90)] and those who earn $25,000 or more [aOR: 1.23 (1.04 -1.45)] had increased odds of high total office visits. Those who have never smoked [aOR: 0.81 (0.69-0.94)] and those from the non-metro region [aOR: 0.65 (0.56-0.76)] had reduced odds of high total office visits. We conclude that those who engage in home BP monitoring are more likely to have a high number of total office visits. The use of home BP monitoring could reflect the severity of high BP suggesting the need for regular follow-up and frequent use of services. Further studies that explore this association are recommended.

Dissertação para obtenção do Grau de Mestre em Engenharia Biomédica
Since mercury thermometers were banned due to environmental concerns, hospitals started to use electronic thermometers for measuring body temperature. Body temperature can be measured from different body parts, although the least invasive and quickest is preferred and therefore eardrum measurements are frequently taken. However, lately the staff feels that the taken measurements are not accurate. A new purchasing agreement for the purchase of these devices renders a good opportunity to study further the use of these devices at the wards of the university hospital, study their maintenance process, identify what performance is essential for the clinical usage, the parameters that are essential to measure and also identify ear thermometers in the market that can be used for comparative study. Temperature measurements were taken with the help of an infrared ear thermometer, Covidien Genius2, in its calibration blackbody device at the R&D department of the Huddinge Hospital in order to verify accuracy claims. This data were compared against other studies and measurements of other infrared ear thermometers devices, the Braun ThermoScan Pro 4000 and also a digital contact thermometer, Welch Allyn Suretemp Plus, applied to different body sites. Informal meetings also took place in order to get more information about the devices and to know where they were used and repaired. It was found that Genius2 measured temperature accurately when compared with a blackbody radiator. Regarding the Braun, it showed an accurate estimate of core temperature in comparison to invasive pulmonary artery catheter thermometry. Electronic tympanic thermometers proved to be a good replacement for conventional methods of thermometry. However, preventive maintenance should occur more often, since the devices are very fragile. Tympanic thermometers are generally very accurate instruments. Most likely, problems are not related to the thermometers themselves, they are possibly the result of an inadequate understanding of the limitations of ear thermometry.

The traditional radiation testing of space electronics has been used for more than fifty years to support the radiation hardness assurance. Its typical goal is to ensure reliable operation of the spacecraft in the harsh environment of space. This PhD research looks into the radiation testing from a different perspective; the goal is to develop radiation testing methods that are focused not only on the reliability of the components but also on a continuous radiation-induced degradation of their performance. Such data are crucial for the understanding of the impact of radiation on the measurement uncertainty of data acquisition systems onboard research space missions.

The master’s thesis deals with ways of controlling starting clutches of cars, especially of DQ200 gearbox, which contains dry disc clutches. The introduction describes basic principles of torque transfer and amount of clutch force. Then the description of construction of starting clutches and ways of controlling clutch types mentioned beforehand is given. In the next part of the thesis, wide spectrum of control methods is measured, from which a certain part is selected. This is followed by driving tests and based on driving data, one method of the clutch control is chosen. Then those control methods from narrow selection are tested for acoustic impact in the cabin of the car. In the end the best way of clutch control is selected. The selection based on driving data and acoustic measurement.

AbstractDrop impact on a hot surface heated above the saturation temperature of the fluid plays an important role in spray cooling. The heat transferred from the wall to the fluid is closely interrelated with drop hydrodynamics. If the surface temperature is below the Leidenfrost temperature, the heat transport strongly depends on the transport phenomena in the vicinity of the three-phase contact line. Due to extremely high local heat flux, a significant fraction of the total heat flow is transported through this region. The local transport processes near the three-phase contact line, and, therefore, the total heat transport, are determined by the wall superheat, contact line velocity, system pressure, fluid composition, surface structure and physical properties on the wall. The effect of the aforementioned influencing parameters on fluid dynamics and heat transport during evaporation of a single meniscus in a capillary slot are studied in a generic experimental setup. The hydrodynamics and evolution of wall heat flux distribution during the impact of a single drop onto a hot wall are also studied experimentally by varying the impact parameters, wall superheat, system pressure, and wall topography. In addition, the fluid dynamics and heat transport behavior during vertical and horizontal coalescence of multiple drops on a heated surface are studied experimentally.

Optical fibre sensors offer the prospect of miniature aerodynamic probes for highly localised flow measurements in aerospace wind tunnels and turbomachines. We discuss the design and construction of optical fibre sensors for temperature and pressure. The temperature sensors consist of multilayer coatings deposited on the fibre end face from which the reflected intensity is temperature-dependent. Two sensors were incorporated in a dual heated probe to measure total temperature. The pressure sensors are miniature diaphragms in which pressure-induced deflection is measured interferometrically in reflection. We present results from initial trials made in unsteady flow in a single stage research turbine, in which total temperature data with harmonic components up to 30 kHz and total pressure signals up to 230 kHz were recorded.

The aspirating probe originally designed by Epstein and Ng at MIT was modified by replacing the two platinum coated tungsten hot wires normally used with platinum iridium alloy wires. The resulting improved unsteady total pressure and total temperature resolution of the modified probe is demonstrated. Flowfield measurements were made downstream of NASA Rotor 37 for a part speed operating condition to test the performance of the probe. Time resolved blade-to-blade total temperature and total pressure as calculated from the two platinum iridium hot wire voltages are shown. The flowfield measurements are compared with independent measurements of total pressure with high response transducers and total temperature calculated from laser anemometer measurements. Limitations of a more often used unsteady temperature data reduction method which involves only one aspirating probe hot wire voltage and a high-response pressure measurement are discussed.

An experimental technique for the measurement of flow total temperature in a turbine facility is demonstrated. Two thin film heat transfer gauges located at the stagnation point of fused quartz substrates are operated at different temperatures in order to determine the flow total temperature. With this technique, no assumptions regarding the magnitude of the convective heat transfer coefficient are made. Thus, the probe can operate successfully in unsteady compressible flows of arbitrary composition and high free-stream turbulence levels without a heat transfer law calibration. The operation of the total temperature probe is first demonstrated using a small wind tunnel facility. Based on results from the small wind tunnel tests, it appears that the probe total temperature measurements are accurate to within ± 1K. Experiments using the probe downstream of a high pressure turbine stage are then described. Both high and low frequency components of the flow total temperature can be accurately resolved with the present technique. The probe measures a time-averaged flow total temperature that is in good agreement with thermocouple measurements made downstream of the rotor. Frequencies as high as 182 kHz have been detected in the spectral analysis of the heat flux signals from the total temperature probe. Through comparison with fast-response aerodynamic probe measurements, it is demonstrated that at the current measurement location, the total temperature fluctuations arise mainly due to the isentropic extraction of work by the turbine. The present total temperature probe is demonstrated to be an accurate, robust, fast-response device that is suitable for operation in a turbomachinery environment.

This paper describes experimental results on total temperature measurement to obtain heat transfer characteristics of turbulent gas flow in a microtube with constant wall temperature. The experiments were performed for nitrogen gas flow through a microtube of 354 μm in diameter with 100 mm in length. The wall temperature was maintained at 310 K, 330 K, and 350 K by circulating water around the microtube, respectively. The stagnation pressure was chosen in such a way that the exit Mach number ranges from 0.1 to 1.0. In order to obtain heat transfer rate of turbulent gas flow through a micro-tube, the total temperatures of gas flowing out of a microtube exit were measured with the set of total temperature measurement attached to micro stage with position fine adjustment. The numerical computations based on the Arbitrary - Langrangian - Eulerian (ALE) method were also performed for the turbulent gas flow with the same conditions of the experiments. The results were in excellent agreement.

This paper describes experimental results on total temperature measurement of nitrogen micro-jet from micro-tubes outlet measured for the wide range from unchoked to choked flow. The experiments were preformed for a stainless micro-tube of 523.2 μm in diameter whose temperature difference between the wall and inlet was maintained at 2, 5 and 10 K by circulating water around the micro-tube, respectively. The gas flows out to the atmospheric condition. A thermally insulated tube of foamed polystyrene with six baffles fabricated by the companion paper (IMECE-36965) where the gas velocity reduces and the kinetic energy is converted into the thermal energy, was attached to the outlet of the micro-tube. The inner diameter of the polystyrene tube is 22 mm. The baffles are equally spaced and the intervals of the baffles tested are 5 and 10 mm to investigate the effect of the interval of the baffle on the reduction of the gas velocity. The gas temperature measured by thermocouples at locations of baffles is considered as total temperature. The measured total temperature is higher than the wall temperature and increases with increasing the stagnation pressure (Reynolds number) for unchoked flow since the additional heat transfer from the wall to the gas near the micro-tube outlet caused by the temperature fall due to the energy conversion into the kinetic energy. It decreases in the insulated tube for chocked flow since Joule-Thomson effect is dominant in the insulated tube. The measured total temperatures are compared with results obtained by numerical computations.

Abstract This work describes a method for calculating pressure fields from temperature and velocity data in non-adiabatic compressible flows, such as the flow around a cooled turbine vane. Prior studies have demonstrated the ability to use particle image velocimetry methods to estimate the pressure gradient in the momentum equation, which is subsequently integrated to produce pressure fields. Due to changes in total temperature for non-adiabatic compressible flows, pressure fields cannot be computed from velocity measurements alone and temperature data must also be provided. In this work, a benchmarked steady 3D RANS simulation is used to generate velocity, temperature, and pressure fields in the transonic flow around a high-pressure turbine inlet guide vane. A procedure for solving the momentum equation and integrating for pressure is developed for non-adiabatic flows. Error is assessed by comparing calculated pressure to CFD predicted pressure, and the effects of PIV spatial resolution and measurement error are considered. The accuracy of the method on non-adiabatic flows is assessed using a vane with extensive film cooling. A clear benefit of incorporating temperature measurements in the pressure determination method is demonstrated, offering opportunities for deeper understanding of aerodynamic losses and entropy generation in cooled turbine flowfields.

This paper presents experimental results on heat transfer characteristics of gaseous flow in a micro-tube with constant wall temperature. The experiment was performed for nitrogen gas flow through a micro-tube with 166 micro meters in diameter and 50mm in length. The wall temperature was maintained at 305K, 310K, 330K and 350K by circulating water around the micro-tube, respectively. The stagnation pressure is chosen in such a way that the exit Mach number ranges from 0.1 to 1.0. The outlet pressure was fixed at the atmospheric condition. The total temperature at the outlet, the inlet stagnation temperature, the mass flow rate, and the inlet pressure were measured. The numerical computations based on the Aribitary - Langrangian - Eulerian (ALE) method were also performed for the same cases of the experiment for validation of numerical computation. The both results are in excellent agreement. The total temperatures obtained by the present study are slightly higher than those of the incompressible flow. This is due to the additional heat transfer near the micro-tube outlet caused by the temperature decrease due to the energy conversion into the kinetic energy. A quantitative correlation for the prediction of the heat transfer rate of the gaseous flow in a micro-tube was proposed.

Total liquid ventilation (TLV) is an experimental mechanical ventilation technique where the lungs are completely filled with a perfluorocarbon liquid (PFC). It can be used to implement moderate therapeutic hypothermia (MTH) and treat severe respiratory problems. During TLV, the airway pressure must be monitored adequately to avoid overpressure and airway collapses. On the thermodynamic level, rectal, esophageal or tympanic temperature measurements are not suitable (long time constant) to avoid lowering the heart below 30°C. The objective was to design a Y connector positioned at the mouth which integrates the virtual sensors, used by controllers. The first estimates the airway pressure and the second provides the core body temperature. Pressure and RTD sensors were installed in the connector to implement the virtual measurements. In-vitro experiments were done to validate the virtual sensors. In-vivo experiments (on newborn lambs) confirm the accuracy of the airway pressure estimation and of the systemic arterial temperature.

Flow exiting the combustor is highly turbulent and contains significant spatial gradients of pressure and temperature. The high pressure turbine nozzle vanes operating in this environment redistribute these spatial gradients and impact the inflow characteristics of the turbine rotor blades. The present study investigates the redistribution of total temperature through a turbine nozzle vane. Numerical investigation was performed using three-dimensional RANS analysis. Simulations were conducted using the Wilcox k–ω turbulence model and Shear Stress Transport (SST) with and without γ–Reθ transition model. Experimental measurements were obtained in an annular nozzle cascade facility. Two sets of inlet conditions were considered. The first was a nominally uniform total temperature. The second had a span-wise variation of total temperature. Both sets of inlet conditions had nominally the same inlet total pressure and inlet Mach number. Span-wise redistribution was evaluated using the circum-ferentially averaged total temperature profile at a plane downstream of the nozzle. Physical arguments about the influence of nozzle secondary flows on this redistribution are presented.

Channel Islands National Park (CHIS) has conducted long-term ecological monitoring of the kelp forests around San Miguel, Santa Rosa, Santa Cruz, Anacapa and Santa Barbara Islands since 1982. The original permanent transects were established at 16 sites between 1981 and 1986 with the first sampling beginning in 1982, this being the 33rd year of monitoring. An additional site, Miracle Mile, was established at San Miguel Island in 2001 by a commercial fisherman with assistance from the park. Miracle Mile was partially monitored from 2002 to 2004, and then fully monitored (using all KFM protocols) since 2005. In 2005, 16 additional permanent sites were established to collect baseline data from inside and adjacent to four marine reserves that were established in 2003. Sampling results from all 33 sites mentioned above are included in this report. Funding for the Kelp Forest Monitoring Program (KFM) in 2014 was provided by the National Park Service (NPS). The 2014 monitoring efforts utilized 49 days of vessel time to conduct 1,040 dives for a total of 1,059 hours of bottom time. Population dynamics of a select list of 71 “indicator species” (consisting of taxa or categories of algae, fish, and invertebrates) were measured at the 33 permanent sites. In addition, population dynamics were measured for all additional species of fish observed at the sites during the roving diver fish count. Survey techniques follow the CHIS Kelp Forest Monitoring Protocol Handbook (Davis et al. 1997) and an update to the sampling protocol handbook currently being developed (Kushner and Sprague, in progress). The techniques utilize SCUBA and surface-supplied-air to conduct the following monitoring protocols: 1 m2 quadrats, 5 m2 quadrats, band transects, random point contacts, fish transects, roving diver fish counts, video transects, size frequency measurements, and artificial recruitment modules. Hourly temperature data were collected using remote temperature loggers at 32 sites, the exception being Miracle Mile where there is no temperature logger installed. This annual report contains a brief description of each site including any notable observations or anomalies, a summary of methods used, and monitoring results for 2014. All the data collected during 2014 can be found in the appendices and in an Excel workbook on the NPS Integrated Resource Management Applications (IRMA) portal. In the 2013 annual report (Sprague et al. 2020) several changes were made to the appendices. Previously, annual report density and percent cover data tables only included the current year’s data. Now, density and percent cover data are presented in graphical format and include all years of available monitoring data. Roving diver fish count (RDFC), fish size frequency, natural habitat size frequency, and Artificial Recruitment Module (ARM) size frequency data are now stored on IRMA at https://irma.nps.gov/DataStore/Reference/Profile/2259651. The temperature data graphs in Appendix L include the same graphs that were used in past reports, but include additional violin plot sections that compare monthly means from the current year to past years. In addition to the changes listed above, the layout of the discussion section was reordered by species instead of by site. The status of kelp forests differed among the five park islands. This is a result of a combination of factors including but not limited to, oceanography, biogeography and associated differences in species abundance and composition, as well as sport and commercial fishing pressure. All 33 permanent sites were established in areas that had or were historically known to have had kelp forests in the past. In 2014, 15 of the 33 sites monitored were characterized as developing kelp forest, kelp forest or mature kelp forest. In addition, three sites were in a state of transition. Two sites were part kelp forest and part dominated by Strongylocentrotus purpuratus...

The original objectives of this research project were to: (1) develop immunoassays, photometric sensors, and electrochemical sensors for real-time measurement of progesterone and estradiol in milk, (2) develop biosensors for measurement of caseins in milk, and (3) integrate and adapt these sensor technologies to create an automated electronic sensing system for operation in dairy parlors during milking. The overall direction of research was not changed, although the work was expanded to include other milk components such as urea and lactose. A second generation biosensor for on-line measurement of bovine progesterone was designed and tested. Anti-progesterone antibody was coated on small disks of nitrocellulose membrane, which were inserted in the reaction chamber prior to testing, and a real-time assay was developed. The biosensor was designed using micropumps and valves under computer control, and assayed fluid volumes on the order of 1 ml. An automated sampler was designed to draw a test volume of milk from the long milk tube using a 4-way pinch valve. The system could execute a measurement cycle in about 10 min. Progesterone could be measured at concentrations low enough to distinguish luteal-phase from follicular-phase cows. The potential of the sensor to detect actual ovulatory events was compared with standard methods of estrus detection, including human observation and an activity monitor. The biosensor correctly identified all ovulatory events during its testperiod, but the variability at low progesterone concentrations triggered some false positives. Direct on-line measurement and intelligent interpretation of reproductive hormone profiles offers the potential for substantial improvement in reproductive management. A simple potentiometric method for measurement of milk protein was developed and tested. The method was based on the fact that proteins bind iodine. When proteins are added to a solution of the redox couple iodine/iodide (I-I2), the concentration of free iodine is changed and, as a consequence, the potential between two electrodes immersed in the solution is changed. The method worked well with analytical casein solutions and accurately measured concentrations of analytical caseins added to fresh milk. When tested with actual milk samples, the correlation between the sensor readings and the reference lab results (of both total proteins and casein content) was inferior to that of analytical casein. A number of different technologies were explored for the analysis of milk urea, and a manometric technique was selected for the final design. In the new sensor, urea in the sample was hydrolyzed to ammonium and carbonate by the enzyme urease, and subsequent shaking of the sample with citric acid in a sealed cell allowed urea to be estimated as a change in partial pressure of carbon dioxide. The pressure change in the cell was measured with a miniature piezoresistive pressure sensor, and effects of background dissolved gases and vapor pressures were corrected for by repeating the measurement of pressure developed in the sample without the addition of urease. Results were accurate in the physiological range of milk, the assay was faster than the typical milking period, and no toxic reagents were required. A sampling device was designed and built to passively draw milk from the long milk tube in the parlor. An electrochemical sensor for lactose was developed starting with a three-cascaded-enzyme sensor, evolving into two enzymes and CO2[Fe (CN)6] as a mediator, and then into a microflow injection system using poly-osmium modified screen-printed electrodes. The sensor was designed to serve multiple milking positions, using a manifold valve, a sampling valve, and two pumps. Disposable screen-printed electrodes with enzymatic membranes were used. The sensor was optimized for electrode coating components, flow rate, pH, and sample size, and the results correlated well (r2= 0.967) with known lactose concentrations.

The test scenarios ranged from fires in the structures with no exterior ventilation to room fires with flow paths that connected the fires with remote intake and exhaust vents. In the ranch, two replicate fires were conducted for each room of origin and each ventilation condition. Rooms of fire origin included the living room, bedroom, and kitchen. In the colonial, the focus was on varying the flow paths to examine the change in fire behavior and the resulting damage. No replicates were conducted in the colonial. After each fire scene was documented, the interior finish and furnishings were replaced in affected areas of the structure. Instrumentation was installed to measure gas temperature, gas pressure, and gas movement within the structures. In addition, oxygen sensors were installed to determine when a sufficient level of oxygen was available for flaming combustion. Standard video and firefighting IR cameras were also installed inside of the structures to capture information about the fire dynamics of the experiments. Video cameras were also positioned outside of the structures to monitor the flow of smoke, flames, and air at the exterior vents. Each of the fires were started from a small flaming source. The fires were allowed to develop until they self-extinguished due to a lack of oxygen or until the fire had transitioned through flashover. The times that fires burned post-flashover varied based on the damage occurring within the structure. The goal was have patterns remaining on the ceiling, walls, and floors post-test. In total, thirteen experiments were conducted in the ranch structure and eight experiments were conducted in the colonial structure. All experiments were conducted at UL's Large Fire Laboratory in Northbrook, IL. Increasing the ventilation available to the fire, in both the ranch and the colonial, resulted in additional burn time, additional fire growth, and a larger area of fire damage within the structures. These changes are consistent with fire dynamics based assessments and were repeatable. Fire patterns within the room of origin led to the area of origin when the ventilation of the structure was considered. Fire patterns generated pre-flashover, persisted post-flashover if the ventilation points were remote from the area of origin.

The primary goals of this project were: (1) development of a genetically characterized association panel of wild emmer for high resolution analysis of the genetic basis of complex traits; (2) characterization and mapping of genes and QTL for seedling and adult plant resistance to stripe rust in wild emmer populations; (3) characterization of LD patterns along wild emmer chromosomes; (4) elucidation of the multi-locus genetic structure of wild emmer populations and its correlation with geo-climatic variables at the collection sites. Introduction In recent years, Stripe (yellow) rust (Yr) caused by Pucciniastriiformis f. sp. tritici(PST) has become a major threat to wheat crops in many parts of the world. New races have overcome most of the known resistances. It is essential, therefore, that the search for new genes will continue, followed by their mapping by molecular markers and introgression into the elite varieties by marker-assisted selection (MAS). The reservoir of genes for disease and pest resistance in wild emmer wheat (Triticumdicoccoides) is an important resource that must be made available to wheat breeders. The majority of resistance genes that were introgressed so far in cultivated wheat are resistance (R) genes. These genes, though confering near-immunity from the seedling stage, are often overcome by the pathogen in a short period after being deployed over vast production areas. On the other hand, adult-plant resistance (APR) is usually more durable since it is, in many cases, polygenic and confers partial resistance that may put less selective pressure on the pathogen. In this project, we have screened a collection of 480 wild emmer accessions originating from Israel for APR and seedling resistance to PST. Seedling resistance was tested against one Israeli and 3 North American PST isolates. APR was tested on accessions that did not have seedling resistance. The APR screen was conducted in two fields in Israel and in one field in the USA over 3 years for a total of 11 replicates. We have found about 20 accessions that have moderate stripe rust APR with infection type (IT<5), and about 20 additional accessions that have novel seedling resistance (IT<3). We have genotyped the collection using genotyping by sequencing (GBS) and the 90K SNP chip array. GBS yielded a total 341K SNP that were filtered to 150K informative SNP. The 90K assay resulted in 11K informative SNP. We have conducted a genome-wide association scan (GWAS) and found one significant locus on 6BL ( -log p >5). Two novel loci were found for seedling resistance. Further investigation of the 6BL locus and the effect of Yr36 showed that the 6BL locus and the Yr36 have additive effect and that the presence of favorable alleles of both loci results in reduction of 2 grades in the IT score. To identify alleles conferring adaption to extreme climatic conditions, we have associated the patterns of genomic variation in wild emmer with historic climate data from the accessions’ collection sites. The analysis of population stratification revealed four genetically distinct groups of wild emmer accessions coinciding with their geographic distribution. Partitioning of genomic variance showed that geographic location and climate together explain 43% of SNPs among emmer accessions with 19% of SNPs affected by climatic factors. The top three bioclimatic factors driving SNP distribution were temperature seasonality, precipitation seasonality, and isothermality. Association mapping approaches revealed 57 SNPs associated with these bio-climatic variables. Out of 21 unique genomic regions controlling heading date variation, 10 (~50%) overlapped with SNPs showing significant association with at least one of the three bioclimatic variables. This result suggests that a substantial part of the genomic variation associated with local adaptation in wild emmer is driven by selection acting on loci regulating flowering. Conclusions: Wild emmer can serve as a good source for novel APR and seedling R genes for stripe rust resistance. APR for stripe rust is a complex trait conferred by several loci that may have an additive effect. GWAS is feasible in the wild emmer population, however, its detection power is limited. A panel of wild emmer tagged with more than 150K SNP is available for further GWAS of important traits. The insights gained by the bioclimatic-gentic associations should be taken into consideration when planning conservation strategies.

In July 2021 the Southeast Coast Network conducted an assessment of water quality in the vicinity of Cape Hatteras and Cape Lookout National Seashores as part of the National Park Service Vital Signs Monitoring Program. Monitoring was conducted following methods developed by the Environmental Protection Agency (EPA) as part of the National Coastal Assessment Program (EPA 2010). Laboratory analysis measured chlorophyll a and total and dissolved concentrations of nitrogen and phosphorous. Field measurements included water temperature, pH, dissolved oxygen, and salinity. Water clarity, which requires a Secchi depth measurement, was obtained when possible. All measured parameters were rated as good, fair, or poor based on thresholds set by the EPA (2012). All measured parameters were rated as good, fair, or poor based on thresholds set by the EPA (2012). Water clarity was not calculated at all sites due to the shallow depth of the water in the sound. Of the sites where water clarity could be assessed (5 sites), four measured good and one fair. Sites that were too shallow to measure water clarity had water column conditions that did not preclude light from penetrating to the bottom of the water body so no ecological effects would be expected.Turbidity measurements ranged from 1.0 to 8.0 FNU (Formazin Nephelometric Units) and are good (i.e. < 25 NTU [Nephelometric Turbidity Units]) according to North Carolina Standards (NC Administrative Code 2019). Note that turbidity units of FNU and NTU are roughly equivalent. Chlorophyll a concentration was rated good at 29 sites (97%), and fair at one site (3%). Dissolved inorganic nitrogen (DIN) concentration was good at all 30 sites (100%). Dissolved inorganic phosphorus (DIP) concentration was good at all 30 sites (100%). Dissolved oxygen concentration (bottom) was rated good at all 30 sites (100%). A water-quality condition summary index was calculated for each site sampled at Cape Hatteras and Cape Lookout National Seashores based on the categorical assessments of chlorophyll a, DIN and DIP concentrations, dissolved oxygen, and water clarity. This summary index indicated good water-quality conditions at all thirty sites (100%). Based on the summary water-quality index rating, overall water-quality conditions at Cape Hatteras and Cape Lookout National Seashores during sampling in 2021 were good. For sediment, ecological condition was ranked as good at 30 sites (100%). As a result, no adverse impacts to benthic organisms due to sediment contamination are anticipated at any of the sampled sites. This ranking was assigned according to the 2010 Environmental Protection Agency, National Coastal Condition Assessment (NCCA) thresholds for sediment chemistry.

In soil solarization, moist soil is covered with a transparent plastic film, resulting in passive solar heating which inactivates soil-borne pathogen/weed propagules. Although solarization is an effective alternative to soil fumigation and chemical pesticide application, it is not widely used due to its long duration, which coincides with the growing season of some crops, thereby causing a loss of income. The basis of this project was that solarization of amended soil would be utilized more widely if growers could adopt the practice without losing production. In this research we examined three factors expected to contribute to greater utilization of solarization: 1) investigation of techniques that increase soil temperature, thereby reducing the time required for solarization; 2) development and validation of predictive soil heating models to enable informed decisions regarding soil and solarization management that accommodate the crop production cycle, and 3) elucidation of the contributions of microbial activity and microbial community structure to soil heating during solarization. Laboratory studies and a field trial were performed to determine heat generation in soil amended with compost during solarization. Respiration was measured in amended soil samples prior to and following solarization as a function of soil depth. Additionally, phytotoxicity was estimated through measurement of germination and early growth of lettuce seedlings in greenhouse assays, and samples were subjected to 16S ribosomal RNA gene sequencing to characterize microbial communities. Amendment of soil with 10% (g/g) compost containing 16.9 mg CO2/g dry weight organic carbon resulted in soil temperatures that were 2oC to 4oC higher than soil alone. Approximately 85% of total organic carbon within the amended soil was exhausted during 22 days of solarization. There was no significant difference in residual respiration with soil depth down to 17.4 cm. Although freshly amended soil proved highly inhibitory to lettuce seed germination and seedling growth, phytotoxicity was not detected in solarized amended soil after 22 days of field solarization. The sequencing data obtained from field samples revealed similar microbial species richness and evenness in both solarized amended and non-amended soil. However, amendment led to enrichment of a community different from that of non-amended soil after solarization. Moreover, community structure varied by soil depth in solarized soil. Coupled with temperature data from soil during solarization, community data highlighted how thermal gradients in soil influence community structure and indicated microorganisms that may contribute to increased soil heating during solarization. Reliable predictive tools are necessary to characterize the solarization process and to minimize the opportunity cost incurred by farmers due to growing season abbreviation, however, current models do not accurately predict temperatures for soils with internal heat generation associated with the microbial breakdown of the soil amendment. To address the need for a more robust model, a first-order source term was developed to model the internal heat source during amended soil solarization. This source term was then incorporated into an existing “soil only” model and validated against data collected from amended soil field trials. The expanded model outperformed both the existing stable-soil model and a constant source term model, predicting daily peak temperatures to within 0.1°C during the critical first week of solarization. Overall the results suggest that amendment of soil with compost prior to solarization may be of value in agricultural soil disinfestations operations, however additional work is needed to determine the effects of soil type and organic matter source on efficacy. Furthermore, models can be developed to predict soil temperature during solarization, however, additional work is needed to couple heat transfer models with pathogen and weed inactivation models to better estimate solarization duration necessary for disinfestation.

1.1 Macroeconomic summary Economic recovery has consistently outperformed the technical staff’s expectations following a steep decline in activity in the second quarter of 2020. At the same time, total and core inflation rates have fallen and remain at low levels, suggesting that a significant element of the reactivation of Colombia’s economy has been related to recovery in potential GDP. This would support the technical staff’s diagnosis of weak aggregate demand and ample excess capacity. The most recently available data on 2020 growth suggests a contraction in economic activity of 6.8%, lower than estimates from January’s Monetary Policy Report (-7.2%). High-frequency indicators suggest that economic performance was significantly more dynamic than expected in January, despite mobility restrictions and quarantine measures. This has also come amid declines in total and core inflation, the latter of which was below January projections if controlling for certain relative price changes. This suggests that the unexpected strength of recent growth contains elements of demand, and that excess capacity, while significant, could be lower than previously estimated. Nevertheless, uncertainty over the measurement of excess capacity continues to be unusually high and marked both by variations in the way different economic sectors and spending components have been affected by the pandemic, and by uneven price behavior. The size of excess capacity, and in particular the evolution of the pandemic in forthcoming quarters, constitute substantial risks to the macroeconomic forecast presented in this report. Despite the unexpected strength of the recovery, the technical staff continues to project ample excess capacity that is expected to remain on the forecast horizon, alongside core inflation that will likely remain below the target. Domestic demand remains below 2019 levels amid unusually significant uncertainty over the size of excess capacity in the economy. High national unemployment (14.6% for February 2021) reflects a loose labor market, while observed total and core inflation continue to be below 2%. Inflationary pressures from the exchange rate are expected to continue to be low, with relatively little pass-through on inflation. This would be compatible with a negative output gap. Excess productive capacity and the expectation of core inflation below the 3% target on the forecast horizon provide a basis for an expansive monetary policy posture. The technical staff’s assessment of certain shocks and their expected effects on the economy, as well as the presence of several sources of uncertainty and related assumptions about their potential macroeconomic impacts, remain a feature of this report. The coronavirus pandemic, in particular, continues to affect the public health environment, and the reopening of Colombia’s economy remains incomplete. The technical staff’s assessment is that the COVID-19 shock has affected both aggregate demand and supply, but that the impact on demand has been deeper and more persistent. Given this persistence, the central forecast accounts for a gradual tightening of the output gap in the absence of new waves of contagion, and as vaccination campaigns progress. The central forecast continues to include an expected increase of total and core inflation rates in the second quarter of 2021, alongside the lapse of the temporary price relief measures put in place in 2020. Additional COVID-19 outbreaks (of uncertain duration and intensity) represent a significant risk factor that could affect these projections. Additionally, the forecast continues to include an upward trend in sovereign risk premiums, reflected by higher levels of public debt that in the wake of the pandemic are likely to persist on the forecast horizon, even in the context of a fiscal adjustment. At the same time, the projection accounts for the shortterm effects on private domestic demand from a fiscal adjustment along the lines of the one currently being proposed by the national government. This would be compatible with a gradual recovery of private domestic demand in 2022. The size and characteristics of the fiscal adjustment that is ultimately implemented, as well as the corresponding market response, represent another source of forecast uncertainty. Newly available information offers evidence of the potential for significant changes to the macroeconomic scenario, though without altering the general diagnosis described above. The most recent data on inflation, growth, fiscal policy, and international financial conditions suggests a more dynamic economy than previously expected. However, a third wave of the pandemic has delayed the re-opening of Colombia’s economy and brought with it a deceleration in economic activity. Detailed descriptions of these considerations and subsequent changes to the macroeconomic forecast are presented below. The expected annual decline in GDP (-0.3%) in the first quarter of 2021 appears to have been less pronounced than projected in January (-4.8%). Partial closures in January to address a second wave of COVID-19 appear to have had a less significant negative impact on the economy than previously estimated. This is reflected in figures related to mobility, energy demand, industry and retail sales, foreign trade, commercial transactions from selected banks, and the national statistics agency’s (DANE) economic tracking indicator (ISE). Output is now expected to have declined annually in the first quarter by 0.3%. Private consumption likely continued to recover, registering levels somewhat above those from the previous year, while public consumption likely increased significantly. While a recovery in investment in both housing and in other buildings and structures is expected, overall investment levels in this case likely continued to be low, and gross fixed capital formation is expected to continue to show significant annual declines. Imports likely recovered to again outpace exports, though both are expected to register significant annual declines. Economic activity that outpaced projections, an increase in oil prices and other export products, and an expected increase in public spending this year account for the upward revision to the 2021 growth forecast (from 4.6% with a range between 2% and 6% in January, to 6.0% with a range between 3% and 7% in April). As a result, the output gap is expected to be smaller and to tighten more rapidly than projected in the previous report, though it is still expected to remain in negative territory on the forecast horizon. Wide forecast intervals reflect the fact that the future evolution of the COVID-19 pandemic remains a significant source of uncertainty on these projections. The delay in the recovery of economic activity as a result of the resurgence of COVID-19 in the first quarter appears to have been less significant than projected in the January report. The central forecast scenario expects this improved performance to continue in 2021 alongside increased consumer and business confidence. Low real interest rates and an active credit supply would also support this dynamic, and the overall conditions would be expected to spur a recovery in consumption and investment. Increased growth in public spending and public works based on the national government’s spending plan (Plan Financiero del Gobierno) are other factors to consider. Additionally, an expected recovery in global demand and higher projected prices for oil and coffee would further contribute to improved external revenues and would favor investment, in particular in the oil sector. Given the above, the technical staff’s 2021 growth forecast has been revised upward from 4.6% in January (range from 2% to 6%) to 6.0% in April (range from 3% to 7%). These projections account for the potential for the third wave of COVID-19 to have a larger and more persistent effect on the economy than the previous wave, while also supposing that there will not be any additional significant waves of the pandemic and that mobility restrictions will be relaxed as a result. Economic growth in 2022 is expected to be 3%, with a range between 1% and 5%. This figure would be lower than projected in the January report (3.6% with a range between 2% and 6%), due to a higher base of comparison given the upward revision to expected GDP in 2021. This forecast also takes into account the likely effects on private demand of a fiscal adjustment of the size currently being proposed by the national government, and which would come into effect in 2022. Excess in productive capacity is now expected to be lower than estimated in January but continues to be significant and affected by high levels of uncertainty, as reflected in the wide forecast intervals. The possibility of new waves of the virus (of uncertain intensity and duration) represents a significant downward risk to projected GDP growth, and is signaled by the lower limits of the ranges provided in this report. Inflation (1.51%) and inflation excluding food and regulated items (0.94%) declined in March compared to December, continuing below the 3% target. The decline in inflation in this period was below projections, explained in large part by unanticipated increases in the costs of certain foods (3.92%) and regulated items (1.52%). An increase in international food and shipping prices, increased foreign demand for beef, and specific upward pressures on perishable food supplies appear to explain a lower-than-expected deceleration in the consumer price index (CPI) for foods. An unexpected increase in regulated items prices came amid unanticipated increases in international fuel prices, on some utilities rates, and for regulated education prices. The decline in annual inflation excluding food and regulated items between December and March was in line with projections from January, though this included downward pressure from a significant reduction in telecommunications rates due to the imminent entry of a new operator. When controlling for the effects of this relative price change, inflation excluding food and regulated items exceeds levels forecast in the previous report. Within this indicator of core inflation, the CPI for goods (1.05%) accelerated due to a reversion of the effects of the VAT-free day in November, which was largely accounted for in February, and possibly by the transmission of a recent depreciation of the peso on domestic prices for certain items (electric and household appliances). For their part, services prices decelerated and showed the lowest rate of annual growth (0.89%) among the large consumer baskets in the CPI. Within the services basket, the annual change in rental prices continued to decline, while those services that continue to experience the most significant restrictions on returning to normal operations (tourism, cinemas, nightlife, etc.) continued to register significant price declines. As previously mentioned, telephone rates also fell significantly due to increased competition in the market. Total inflation is expected to continue to be affected by ample excesses in productive capacity for the remainder of 2021 and 2022, though less so than projected in January. As a result, convergence to the inflation target is now expected to be somewhat faster than estimated in the previous report, assuming the absence of significant additional outbreaks of COVID-19. The technical staff’s year-end inflation projections for 2021 and 2022 have increased, suggesting figures around 3% due largely to variation in food and regulated items prices. The projection for inflation excluding food and regulated items also increased, but remains below 3%. Price relief measures on indirect taxes implemented in 2020 are expected to lapse in the second quarter of 2021, generating a one-off effect on prices and temporarily affecting inflation excluding food and regulated items. However, indexation to low levels of past inflation, weak demand, and ample excess productive capacity are expected to keep core inflation below the target, near 2.3% at the end of 2021 (previously 2.1%). The reversion in 2021 of the effects of some price relief measures on utility rates from 2020 should lead to an increase in the CPI for regulated items in the second half of this year. Annual price changes are now expected to be higher than estimated in the January report due to an increased expected path for fuel prices and unanticipated increases in regulated education prices. The projection for the CPI for foods has increased compared to the previous report, taking into account certain factors that were not anticipated in January (a less favorable agricultural cycle, increased pressure from international prices, and transport costs). Given the above, year-end annual inflation for 2021 and 2022 is now expected to be 3% and 2.8%, respectively, which would be above projections from January (2.3% and 2,7%). For its part, expected inflation based on analyst surveys suggests year-end inflation in 2021 and 2022 of 2.8% and 3.1%, respectively. There remains significant uncertainty surrounding the inflation forecasts included in this report due to several factors: 1) the evolution of the pandemic; 2) the difficulty in evaluating the size and persistence of excess productive capacity; 3) the timing and manner in which price relief measures will lapse; and 4) the future behavior of food prices. Projected 2021 growth in foreign demand (4.4% to 5.2%) and the supposed average oil price (USD 53 to USD 61 per Brent benchmark barrel) were both revised upward. An increase in long-term international interest rates has been reflected in a depreciation of the peso and could result in relatively tighter external financial conditions for emerging market economies, including Colombia. Average growth among Colombia’s trade partners was greater than expected in the fourth quarter of 2020. This, together with a sizable fiscal stimulus approved in the United States and the onset of a massive global vaccination campaign, largely explains the projected increase in foreign demand growth in 2021. The resilience of the goods market in the face of global crisis and an expected normalization in international trade are additional factors. These considerations and the expected continuation of a gradual reduction of mobility restrictions abroad suggest that Colombia’s trade partners could grow on average by 5.2% in 2021 and around 3.4% in 2022. The improved prospects for global economic growth have led to an increase in current and expected oil prices. Production interruptions due to a heavy winter, reduced inventories, and increased supply restrictions instituted by producing countries have also contributed to the increase. Meanwhile, market forecasts and recent Federal Reserve pronouncements suggest that the benchmark interest rate in the U.S. will remain stable for the next two years. Nevertheless, a significant increase in public spending in the country has fostered expectations for greater growth and inflation, as well as increased uncertainty over the moment in which a normalization of monetary policy might begin. This has been reflected in an increase in long-term interest rates. In this context, emerging market economies in the region, including Colombia, have registered increases in sovereign risk premiums and long-term domestic interest rates, and a depreciation of local currencies against the dollar. Recent outbreaks of COVID-19 in several of these economies; limits on vaccine supply and the slow pace of immunization campaigns in some countries; a significant increase in public debt; and tensions between the United States and China, among other factors, all add to a high level of uncertainty surrounding interest rate spreads, external financing conditions, and the future performance of risk premiums. The impact that this environment could have on the exchange rate and on domestic financing conditions represent risks to the macroeconomic and monetary policy forecasts. Domestic financial conditions continue to favor recovery in economic activity. The transmission of reductions to the policy interest rate on credit rates has been significant. The banking portfolio continues to recover amid circumstances that have affected both the supply and demand for loans, and in which some credit risks have materialized. Preferential and ordinary commercial interest rates have fallen to a similar degree as the benchmark interest rate. As is generally the case, this transmission has come at a slower pace for consumer credit rates, and has been further delayed in the case of mortgage rates. Commercial credit levels stabilized above pre-pandemic levels in March, following an increase resulting from significant liquidity requirements for businesses in the second quarter of 2020. The consumer credit portfolio continued to recover and has now surpassed February 2020 levels, though overall growth in the portfolio remains low. At the same time, portfolio projections and default indicators have increased, and credit establishment earnings have come down. Despite this, credit disbursements continue to recover and solvency indicators remain well above regulatory minimums. 1.2 Monetary policy decision In its meetings in March and April the BDBR left the benchmark interest rate unchanged at 1.75%.