Rate Meter Research Articles

Evaluation of fluence-to-dose response function of neutron survey meter using singular value decomposition method

This paper presents the evaluation of the fluence-to-ambient dose equivalent response function (referred to as F2D response function) of the Aloka TPS-451C neutron dose equivalent rate meter (hereafter referred to as a neutron meter) based on a singular value decomposition (SVD) approach. Measurements of neutron ambient dose equivalent rates, Ḣ∗(10), using the neutron meter were conducted in various neutron standard fields of 241Am-Be source with different neutron fluence rate spectra. A series of Ḣ∗(10) values and corresponding neutron fluence rate spectra were used as the input data for unfolding the F2D response function of the neutron meter. To verify the SVD-based method, the fluence response functions of a well-known Bonner sphere spectrometer system were unfolded using the SVD method, and the results were compared with those provided in the IAEA technical report No. 403. The SVD method was then applied to determine the F2D response function of the Aloka TPS-451C neutron meter with the use of the ICRP-74 F2D response function and that predicted in a previous work as initial guesses. The consistency between initial guesses and the SVD unfolded F2D response function of the Aloka TPS-451C neutron meter implies the reliability of the SVD method for determining the response functions of neutron meters.

A new approach to predict pump transient phenomena in Molten salt reactor Experiment (MSRE) by missing data identification and regeneration

Molten Salt Reactor Experiment (MSRE) is being extensively used for validating the computational tools for Molten Salt Reactors (MSRs). The pump transient tests were performed during the operation of MSRE to obtain the reactivity response to flow perturbation. The transient flow rate during this set of tests is required as input to predict the reactivity response. Since the primary loop of MSRE was not equipped with a flow rate meter, the transient flow rate, which is the crucial factor for the reactivity change in MSRE, is missing. Achieving an accurate simulation of the reactivity response to the MSRE pump transient tests necessitates a precise estimation of the transient flow rate.This paper endeavors to reconstruct the missing flow rate with the aim of offering a valuable input for simulating reactivity responses in the pump transient test series. In order to obtain an accurate transient flow rate, we employed a centrifugal pump transient model based on the affinity laws and solved the model for the MSRE secondary pump to validate the underlying assumptions of the model. In addition, we constructed the homologous pump head curves based on the water test data for the same purpose. The affinity law approximation is proved to be adequate in predicting the MSRE pump startup transient with the root-mean-square error (RMSE) in the normalized flow rate to be 0.03. On the other hand, for the MSRE pump coastdown transient, the preliminary results indicate that neither the affinity law approximation nor the homologous head curve is sufficient to provide acceptable predictions. To overcome this noticeable modeling deficit, we propose an innovative approach based on a straightforward data mining technique to regenerate the MSRE pump coastdown homologous relations using the measured data of the secondary pump. These relations are transferred to the primary pump and used to simultaneously solve for the impeller speed and the flow rate of the pump in the primary pump coastdown. With the new approach, the estimated RMSE in the normalized pump speed for the primary pump coastdown is reduced 0.0052. This excellent agreement validates the accurate calculations for the flow rate during the pump coastdown transient. We also performed an uncertainty analysis to quantify the confidence interval of the predicted quantities, which further justifies the robustness of the proposed approach.

Communication-Based Distributed Consensus Control Supported by High-Reporting Rate Meters in Islanded Microgrids

Communication-Based Distributed Consensus Control Supported by High-Reporting Rate Meters in Islanded Microgrids

Developing and using international standards for neutron ambient dose equivalent rate meters

Measurements of neutron ambient dose equivalent rates are challenging because there are no perfect instruments that cover the entire 9 orders of magnitude neutron energy range (thermal to 20 MeV). Hence quantifying performance requirements with the international standard IEC 61005 for neutron ambient dose equivalent rate meters presents unique challenges. This paper discusses the requirements of this standard, which have been refined and improved over the last 20 years. Examples of type testing results for the constancy of ambient dose rate response, variation of the response due to neutron energy, response time, and various environmental disturbances are examined. IEC 61005 provides manufacturers with internationally acceptable requirements and provides consistent test methods for compliance with stated performance requirements.

Electrochemical Exfoliation and Growth of Nickel–Cobalt Layered Double Hydroxides@Black Phosphorus Hetero‐Nanostructure Textiles for Robust Foldable Supercapacitors

AbstractAdvanced innovation of flexible electrode with adequate redox activity and stably mechanical endurance that promotes charges kinetic migration and faradaic storage is pivotal for textile‐based supercapacitors (T‐SCs). Herein, this study reports a high‐performance T‐SCs electrode based on nickel–cobalt layered double hydroxides@black phosphorus (NiCo‐LDHs@BP) on a conductive silk (c‐silk) textile (NiCo‐LDHs@BP/c‐silk). Under negative voltage‐induced electrochemical exfoliation, the Ni2+ and Co2+ are embedded into bulk BP framework to form exfoliated BP nanosheets, and the NiCo‐LDHs are in situ grown within the BP networks, generating 3D NiCo‐LDHs@BP hetero‐nanostructure. Significantly, the NiCo‐LDHs@BP exhibits a large space‐charge area, enhanced adsorption energy for OH− and accelerated charges transfer/storage as confirmed using density functional theory calculations. Additionally, the T‐SCs electrode is fabricated by loading the blended NiCo‐LDHs@BP, sericin, and carbon nanotubes on fibroin textile via a silk reconstruction strategy, producing large area production, superior mechanical flexibility, and impressive electrochemical performance. The resultant NiCo‐LDHs@BP/c‐silk electrode exhibits large specific capacitance of 1291.3 F g−1 and considerable rate capacity in 1 M KOH electrolyte. Furthermore, the flexible solid‐state asymmetric T‐SCs deliver high specific areal energy density of 279.6 µWh cm−2 and robust folding capability (85.6% capacitance retention after 5000 folding cycles), which successfully power wearable watch and heart rate meter devices.

Research on multi-probe energy response compensation for X/γ dose rate meter

Dose rate meters operating in pulse counting mode usually encounter the problem of uneven energy response. While current methods of coating a single probe with a metal layer can effectively improve the flatness of the energy response, the energy range of the flat response is limited. In this research, a multi-probe energy response compensation method was proposed to solve the problem of uneven energy response of a CsI(Tl) dose rate meter. In this method, different relative energy response curves were obtained by adding different hardware compensations to a probe. Then, two to four relative energy response curves were selected and weighted to obtain a flatter response within the energy region of interest. Specifically, first, 51 compensation schemes were obtained by changing the geometry and material parameters of the CsI(Tl) probe compensation layer. Second, the relative energy response curves of CsI(Tl) probes with 51 compensation schemes were obtained by MCNP simulation. Finally, the weight coefficient of each relative energy response curve was determined by overdetermined equations, and the combination with the smallest relative energy response deviation was selected. Within the energy range of 80–1500 keV, the optimal two-probe compensation scheme was selected from one to three probe compensation schemes. After the dual probe combination compensation, the relative energy response deviation ranged from -23.0% to 5.0%. Within the energy range of 50–3000 keV, the compensation schemes of one to four probes were traversed. The optimal three-probe compensation schemes were selected. After combined compensation, the relative energy response deviation ranged from -27.3% to 15.3%. Furthermore, the compensation effect of multiple probes was better than that of single probes in both energy regions of interest. Simulation results demonstrated that our proposed method can significantly improve the flatness of the energy response of dose rate meters based on CsI(Tl).

A Real-Time Energy Response Correction Method for Cs3Cu2I5:Tl Scintillating Dosimeter.

The uneven energy response of radiation detectors severely limits the accuracy of the dose rate meter used for radiation protection. Currently widely used in dose rate meters as a physical method of setting shielding compensation, the energy response correction error of the detector at different energies is mostly between 15 and 25%. This work designs a real-time correction method for energy response based on a novel Cs3Cu2I5:Tl scintillation detector to improve the accuracy of the dose rate meter used for radiation protection. The technique utilizes the idea of pulse amplitude weighting (PAW) to segment the pulse amplitude histogram. This detector achieves an almost constant energy response after our correction. The experimental results show that compared to 137Cs γ rays, the maximum error of the response is 8.26% in the photon energy ranging from 33 keV to 1.25 MeV, which is much better than ±30% of the recommended IEC 61526:2010, verifying the feasibility of PAW.

Balanced Scorecard Analysis To Assess The Performance Of Tirta Hidayah Regional Public Company (Perumda), Bengkulu City

Measuring company performance is important in a company, both government and private agencies, because by measuring performance it can be seen the effectiveness of strategy determination and its implementation. The aim of the research is to analyze and describe the performance of Perumda Tirta Hidayah Bengkulu City by using the balanced scorecard method.This research was conducted at the office of Perumda Tirta Hidayah Hibrida Street 15 No. 81 Sidomulyo Village, Gading Cempaka District, Bengkulu City. The research instrument uses the Balanced Scorecard developed by BPPSPAM (2013), namely financial aspects, operational aspects, service aspects and HR aspects in 2021-2022. Data collection through documentation, observation and literature study and data analysis using quantitative descriptive analysis method.The results of the study revealed that the performance of Perumda Tirta Hidayah Bengkulu City using the balanced scorecard method in 2022 was in the healthy category (3.33) and in 2021 in the healthy category (3.17). The financial aspect with three indicators (cash ratio, collection effectiveness and solvency) has good performance, and two indicators (ROE and operating ratios) have poor performance. The service aspect with three indicators (technical service coverage, complaint settlement rate and customer water quality) has good performance, and two indicators (subscriber growth and domestic water consumption) have poor performance. The operational aspect has three indicators (production efficiency, service operating hours and customer water pressure) performing well, and two indicators (water loss rate and water meter replacement) performing poorly. The HR aspect with two indicators (the ratio of the number of employees and the training and education staff ratio) performs well, and one indicator (training costs to personnel costs) performs poorly. Keywords : Balanced Scorecard, Company Performance, Perumda Tirta Hidayah

ANALISIS PENGARUH TEMPERATUR RUANGAN DAN JENIS KEGIATAN TERHADAP CYBERSICKNESS DAN KELELAHAN FISIK

When carrying out activities in the virtual world, there is a gap between VR device technology and the human body's ability to respond to the virtual world's display, which is called cybersickness. This study uses factors that arise from outside VR, namely physical environmental factors regarding room temperature. In addition, factors that arise from within VR are also used, namely the type of work. This research is experimental with the number of volunteers as many as 9 people. The sampling technique used was purposive sampling and the volunteers had an age range between 20-25 years. The research was conducted using a virtual reality device and a heart rate meter. The variable used is the temperature variable (warm comfortable and optimal comfortable). The software used for this research is Job Simulator by simulating the type of work as a mode variable (type of work), namely office workers and store clerks. The results of the twoway ANOVA test show that the temperature variable, the mode variable, and the interaction between the two variables have no effect on cybersickness and physical fatigue. The results of the paired t-test show that the heart rate before and during the activity is the same. The results of the energy calculation show that each scenario carried out is included in the classification of "light" work levels and the results of the overall average heart rate show that each scenario carried out is included in the classification of "low/low" workload. The results of theoretical rest time calculations show that almost all volunteers do not need rest. It is concluded that playing Virtual Reality at warm and comfortable temperatures is optimal, and the office worker and store clerk job types have not caused significant cybersickness as long as the game is played for 15-20 minutes.

Iot Based Flood Detection, Alarm and Monitoring System Using Multilayer Perceptron and Regression

Flooding is a common natural event caused by heavy rainfall and high tides in the Philippines. While this disaster cannot be prevented, people can prepare themselves to face it. The City of Ilagan in the province of Isabela is one of the highly prone areas to flooding caused by the welling of the Cagayan River. Many communities are living in low-lying areas which most likely experiencing floods. An analysis of the location is conducted including the people living in the area. The analysis resulted in the development of an IoT-based technology for detection and early warning signals to people using sms notifications that can help lessen the difficulty of evacuation. The system uses Arduino UNO as a microcontroller where sensors are attached. These sensors are Light Detection and Ranging (LiDAR) for flood level measurement in feet (ft), Rain Gauge to measure the precipitation rate (mm/hr), and Flow Rate Meter to measure the fluctuation flow of the river in (L/hr). Data gathered from these sensors are processed and sent immediately to people living nearby to monitor the flood level in real-time. The predictive models are developed using the Pinacanauan River dataset taken from the river stations. The multilayer perceptron is used to develop the predictive model with 99% accuracy. The data from sensors are used also and processed using linear regression and calculated as 88% accurate and significant for prediction.

Characterization of the radiation field surrounding the Leksell Gamma Knife® and shielding applications

The aim of this study is to improve the characterization and modeling of the radiation field surrounding the Leksell Gamma Knife®-PerfexionTM. The improved characterization of the radiation field enables more accurate shielding calculations to be performed for the areas adjacent to the treatment room. With the aid of a high-purity germanium detector and a satellite dose rate meter, γ-ray spectra and ambient dose equivalent H*(10) data were acquired at various locations in the field of a Leksell Gamma Knife unit in a treatment room at Karolinska University Hospital, Sweden. These measurements were used to validate the results of the PEGASOS Monte Carlo simulation system with a PENELOPE kernel. The levels of the radiation that passes through the shielding of the machine (leakage radiation) are shown to be much lower than what is suggested by various bodies, e.g. the National Council on Radiation Protection and Measurements, to be used when calculating radiation shielding barriers. The results clearly indicate that Monte Carlo simulations may be used in structural shielding design calculations for γ rays from the Leksell Gamma Knife.

Effects of Shoes with Added Mass on the Performance of Badminton Basic Footwork

<p>目的：本研究探討穿不同加重之羽球鞋 (加重0g、50g、100g、150g、200g、250g)，對大專羽球運動員從事基本步法表現之影響。方法：本研究招募 40 位大專羽球運動員 (男22位、女18位)，受測球員分別穿不同加重之羽球鞋執行基本步法測試，加重方法是以數個金屬棒以套袋附加於鞋後方的鞋面上。實驗過程透過分段計時器及無線心率計，分別記錄完成指定基本步法所需的時間及心跳率。結果：完成指定步法所需的時間，男性顯著比女性快 (p< .05)，當加重超過50g，完成步法時間與未加重即達顯著差異 (p< .05)，且加重愈重完成時間愈久。不同性別在心率的變化上未達顯著差異 (p> .05)，心率的變化在加重超過50g時，與未加重即達顯著差異 (p< .05)，且開始測試後10秒的心率上升變化即有顯著差異 (p< .05)。結論：運動員穿加重50g以上的羽球鞋，會對基本步法的表現產生影響，鞋子加重的介入似乎可刺激運動員生理反應的變化，以提升訓練之效果。</p> <p> </p><p>Purposes: This study investigated how varied masses (0g, 50g, 100g, 150g, 200g, and 250g) added to badminton shoes can have an effect on the basic footwork performances of college badminton players. Methods: 40 college badminton players (22 males and 18 females) were recruited to do the test, wearing shoes with varied mass to perform some designated basic footwork on the badminton court. During the experiment, the time required for the players to complete the basic footwork and their individual heart rates were recorded by a segmented timer system and a wireless heart rate meter, respectively. Results: The results showed that it required significantly less time for male players than for female players to complete the basic footwork (p < .05). When the mass added to the shoes was over 50g, the time required for players to complete the designated footwork was significantly greater from the time required when there was no mass added to the shoes (p < .05), and increased mass added to the shoes resulted in an increased amount of time for players to complete the basic footwork. On the other hand, there was no significant difference in the change of heart rate between male players and female players (p>.05). When players wore shoes with added mass of more than 50g (p<.05), they showed obvious changes of heart rate, which were significantly greater when they wore shoes without any additional mass. Moreover, there was a significant difference (p < .05) in the changes of their heart rates—a rise in 10 seconds after the test started. Conclusions: In conclusion, wearing shoes with added mass of more than 50g can have an impact on badminton players’ performances of the designated basic footwork. The intervention of weighted badminton shoes seems to have stimulated the players’ physiological responses and thus improved the training effect.</p> <p> </p>

The Effectiveness of Nesting and Lighting in Physiological Function for Low Birth Weight Babies in Sidoarjo

One of the goals of the Millennium Development Goals (MDG's) is to lower infant and child mortality rates. In 2006 according to the World Health Organization (WHO) infant mortality rate in the world was 49 per1000 births and the most cause of death was Low Birth Weight Babies. In Sidoarjo Hospital the birth rate of BBLR in the last 3 months is still high ranging from 30-38 babies. This study aims to analyze the effectiveness of nesting and lighting in physiological function for LBW babies in RSUD Sidoarjo. This type of research is a quasy experiment with a nonrandomized pretest and posttest with control group design with purposive sampling in the Infant Room and NICU of Sidoarjo Hospital as many as 61 (40 control groups and 21 intervention groups). Measuring instruments used are luxmeters, heart rate meters, oximeters, thermometers and observation sheets. The independent variables are the use of light shields and nesting and the dependent variables are pulse frequency and oxygen saturation. The results showed there was a difference in value between pre and post test heart rate and oxygen saturation in the intervention group with a value of p< 0.05 and there was a difference between the control group and the intervention group in the respiration rate counts pre and post intervention, the post heart rate intervention, and the post temperature intervention with a value of p<0.05. The physiological condition of the baby is related to temperature, respiration and relatively stable heart rate and the use of nesting and light protection affects the physiological stability of the heart rate and oxygen saturation

A simple and low-cost directional detection technique for radiation source localization for nuclear security applications

One of the goals in the field of nuclear security is to prevent the misuse and loss of nuclear or other radiological materials. If lost or stolen, radioactive materials could be located and secured using radiation detectors like count rate meters or imaging systems. However, such detectors may not allow for the swift localization of lost sources or may be cost prohibitive in many measurement scenarios. A simple, low-cost, directional radiation detector that is capable of quickly “pointing” towards the nearest radiation source is sought for source search scenarios. Such a detector can be realized using a plastic scintillator couple on each end to photo-multiplier tubes, as shown in this work. The event-by-event position of scintillation in this study is approximated by averaging the amount of light arriving at each of the photomultiplier tubes during coincidence counting. The detector system is then rotated so that the approximated scintillation positions within the detector volume can be determined in other spatial dimensions. A guess vector generated by comparing light ratio skewness produced by the detector in orthogonal orientations points in the direction of a nearby radiation source. An MCNPX-PoliMi model was used to guide the design of such a detector and validate the guess-vector technique. A prototype system using a cube of an EJ-204 plastic scintillator and two photomultiplier tubes was constructed and a correlation between azimuthal source position and detector response was established. For measurements of tens of thousands of counts, the detector prototype generates guess vectors that can identify source position to within 5° uncertainty. The detector prototype can determine the general direction of a nearby source to within 45° uncertainty using 1000 total counts.

The Cloud FIBER-FIT Model for Physical Fitness Check-Up.

Physical fitness refers to the ability of the body to perform tasks or do one of the physical activities well without being tired quickly. The objective of this research is to develop a physical fitness instrument for measuring oneself heart rate, grip strength, and reaction time that could develop a model for a self-check-up on physical fitness which helps to plan the improvement for health which is called the "FIBER-FIT" model. The physical fitness measuring instrument is composed of three modules; (1) heart rate meter module using a green light emitting diode and a photosensor, (2) grip strength meter module using a load cell transducer, and (3) reaction time meter module using a computer graphical function. All modules are controlled by computer programming, LabVIEW. The program could measure the physical fitness parameters in real-time and display the results in graphs, values on a computer monitor. The data could be recorded on cloud storage and could be retrieved for viewing and analyzing from anywhere via the internet. Getting the "FIBER-FIT" model, a physical fitness measuring instrument to evaluate and analyze the results in real time. Overall performance test results were comparable to the standard commonly used instruments. The satisfaction survey scores from the participants were 33.33% and 66.67% for the highest level and the high level, respectively. The Cloud "FIBER-FIT" model is recommended for physical fitness applications for health improvement.

Quantification of Flow Rates and Flow Volumes in Valve Regurgitation Using 3-D High Frame-Rate Ultrasound

Valve regurgitation is a cardiac condition caused by the incomplete closure of a cardiac valve. Untreated, this condition may result in cardiac failure. Regular monitoring of this condition is essential in guiding the decision process for surgical intervention. Current guidelines recommend a multiparametric assessment of valve regurgitation using echocardiography, which is both time consuming and heavily dependent on the experience of the examiner. Several methods have been proposed to provide quantitative markers to facilitate the assessment of valve regurgitation, most notably the Proximal Isovelocity Surface Area (PISA) method and methods based on the quantification of the total Regurgitant Volume (RVol) from the power of backscattered blood signal. In this work, we propose a framework based on trans-thoracic 3-D high frame-rate acquisitions for the simultaneous estimation of the jet cross-sectional area and jet velocity directly at the jet core, which are then combined to estimate the instantaneous flow rate and RVol patients with aortic or mitral insufficiency. We compare two methods for the segmentation of the jet cross-sectional area from the power Doppler signal. Validation on simulated data indicates good segmentation accuracy for the best method (β = 0.97, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> = 0.91). Validation on recordings from a flow phantom shows good agreement (β = 1.2, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">R</i> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> = 0.88) with an external flow rate meter. Clinical feasibility of the method is also shown in a patient with mitral regurgitation.

Distributed Consensus Control Supported by High Reporting Rate Meters in Inverter-Based Cyber-Physical Microgrids

Distributed Consensus Control Supported by High Reporting Rate Meters in Inverter-Based Cyber-Physical Microgrids

Sistem Pengukuran Detak Jantung Berbasis Visual Menggunakan Plane Orthogonal to Skin dan Peak

Measurement of vital signs is a procedure that is usually done when health workers carry out screening. The vital signs in question include body temperature, heart rate, blood pressure, oxygen saturation and others. The equipment used to measure these vital signs should generally be touched to the subject (by contact). However, due to the COVID-19 pandemic, contact measurements need to be avoided. So it is necessary to make a non-contact measuring system for vital signs. In this study, the only vital signs measured were heart rate. In this study it is proposed to make a non-contact heart rate meter with a plane orthogonal to skin (POS) that uses a peak detection algorithm to determine the heart rate value. In general, the POS method using the fast Fourier transform (FFT) requires longer data which makes the process take longer. So in this study, a peak detection algorithm will be used to calculate the heart rate value that has been extracted using POS which has a faster process. Based on the testing of the POS-FFT method and the POS-peak detection method, it was found that POS-peak detection gave stable results at all data lengths. The smallest mean absolute error generated is with a data length of 128 which is 5.19 bpm

Preliminary validation of the 1D modeling of the DYNASTY natural circulation loop against results from water experimental campaign

In the continuous improvements of the safety of nuclear power plants, the study of natural circulation is of primary importance for developing passive safety systems and Generation-IV reactors, such as the Molten Salt Fast Reactor (MSFR). In particular, removing the decay heat during the shutdown of the MSFR involves dealing with a circulating fuel driven by natural circulation; as such, the development and validation of natural circulation models are of primary importance. To validate models and provide experimental data on natural circulation with a distributed heat source, the DYNASTY (DYnamics of NAtural circulation for molten SalT internallY heated) natural circulation loop has been built on the premises of Politecnico di Milano. This paper focuses on improving the 1D modeling of natural circulation phenomena in the DYNASTY facility and validating them against the results (also reported in this work) found in the first experimental campaign, carried out with water as the working fluid. The modeling of DYNASTY is based on a 1D approach using DYMOLA®, a modeling environment based on the MODELICA simulation language. The models used are improved versions of the ones available in the literature, which better model the experimental facility as they now include the mass flow rate meter, the heat loss between the facility and the environment, and a more realistic cooler. The improved model was then used to study the outcomes of the model simulations and verify the influence of the different numerical integration algorithms on the simulation results. The first DYNASTY experimental campaign provides in-depth testing of its behavior, with different cooling fan speeds and considering all possible heating configurations. The collected results for the heating and cooling transients are the mass flow rate and four fluid temperatures measured by thermocouples placed at the beginning and the end of the four DYNASTY legs. The experimental results were compared with the model simulations, showing the good predicting capabilities of the latter one following the tuning of the heat exchange model. In particular, the comparison showed an excellent match between the model and the experimental results for the heating transient while showing improving margins for the cooling transient.

Comprehensive investigation on ballistic injection characteristics of GDI injector: A particular focus on injection pressure and fuel effects

The ballistic injection occurs in the short injection pulse conditions of solenoid-actuated fuel injectors, in which the injection mass does not have a linear relationship with the coil energizing time (injection pulse duration). Sometimes, a reversal stage appears in the ballistic regime in which the injection mass temporarily decreases against the increase of injection pulse duration. Previous studies have observed these nonlinear injection characteristics but insufficient attention has been paid to what are the related mechanisms and how they appear differently based on injection parameters. Understanding these is of great importance for the advanced design and control of fuel injectors in conventional and alternative fuel engines, particularly applying the short-pulse multiple injection strategies. The current study investigates the injection pressure and fuel effects on ballistic and linear injection characteristics of a gasoline direct injection injector using a Bosch long-tube injection rate meter. In the long-pulse linear injection regime, the injection pressure effect showed a typical trend but the fuel effects appeared insignificant. However, these injection pressure and fuel effects appeared more complicated and dramatic in the ballistic regime. The increase in the injection pressure showed a slower needle rise which caused a shorter injection duration and the appearance of the reversal stage at a longer injection pulse duration. The higher fuel viscosity caused a longer injection delay, which resulted in a shorter injection duration, lower injection mass, and the appearance of the reversal stage at a longer injection pulse duration. The needle dynamics associated with the ballistic injection characteristics and their dependence on injection parameters were thoroughly discussed based on the results.