Implementing quantile selection models in Stata

In this article, we describe qregsel, a community-contributed command that implements a copula-based sample-selection correction for quantile regression recently proposed by Arellano and Bonhomme (2017, Econometrica 85: 1–28). The command allows the user to model selection in quantile regressions by using either a Gaussian or a one-dimensional Frank copula. We illustrate the use of qregsel with two examples. First, we apply the method to the fictional dataset used in the Stata Base Reference Manual for the heckman command. Second, we replicate part of the empirical application of the original article using data for the United Kingdom that cover the period 1978–2000 to compare wages of males and females at different quantiles.

InaCORS-BIG Service For Practice Survey

Badan Informasi Geospasial (BIG) is a government agency engaged in the field of Geospatial Information (IG). BIG provides several services that can be accessed by the general public and related to IG. One of the services provided by BIG is the Indonesia Continuously Operating Reference System (InaCORS). InaCORS is divided into various services, as Rinex data services, Online Post-Processing, RTK NTrip, and Mobile InaCORS. This study aims to determine the effectiveness and accuracy of InaCORS services for GNSS surveys using the Rapid Static method and Network RTK. The rapid static survey data is processed using online post-processing services and Network RTK (iMax, Max, and Nearest) will use InaCORS points as a base reference. This study also uses the results of the Total Station tool as comparison data. The results showed that the average value of the difference between the rapid static coordinates and the TS observations was dN = 0.353 m dE = 0.180 m and dZ = 0.233 m, while the Network RTK and TS coordinates were dN = 0.408 m dE = 0.184 m and dZ = 0.176 m.

Reliability of Different Anterior Cranial Base Reference Areas for Voxel-Based Superimposition

The study aimed to evaluate the reliability and reproducibility and compare the outcomes of two 3D voxel-based superimposition techniques for craniofacial CBCT images, using anterior cranial base areas of different extent as references. Fifteen preexisting pairs of serial CBCTs (initial age: 11.7 ± 0.6 years; interval: 1.7 ± 0.4 years) were superimposed on total anterior cranial base (TACB) or middle anterior cranial base (MACB) structures through the Dolphin 3D software. The overlap of the reference structures was assessed visually to indicate reliability. All superimpositions were repeated by the same investigator. Outcomes were compared to assess the agreement between the two methods. Reliability was perfect for the TACB and moderate for the MACB method (p = 0.044). Both areas showed good overall reproducibility, though in individual cases there were notable differences for MACB superimpositions, ranging from −1.84 to 1.64 mm (TACB range: −0.48 to 0.31 mm). The overall agreement in the detected T0/T1 changes was also good, though it was significantly reduced for individual measurements (median < 0.01 mm, IQR: 0.46 mm, range: −2.81 to 0.73 mm). In conclusion, the voxel-based superimposition on TACB was more reliable and showed higher reproducibility than the superimposition on MACB. Thus, the extended anterior cranial base area is recommended for the assessment of craniofacial changes.

Highly Transient High Speed Jet Flow From Different Orifice Geometries

The majority of the many types of different industrial flows are not in the laminar flow regime, but rather these flows are well beyond laminar and continue to exceed the turbulent flow transition criterion for internal and free shear flows to be fully turbulent and highly unsteady involving the transfer of fluid through circular conduits or round pipes as well as other conduit geometries including the issuing of jet flows into some type of ambient environment. High speed jet flows have a wide range of applications in many areas of engineering. The understanding of jet flow theory has progressed substantially. However, there is a very little investigation into the transient nature of the high-speed jet flows and how the structure of these jet flows differs according to the geometry of the orifice out of which the jet flow emanates. The transient nature of these jet flows allows the applications into which they are installed to be optimized according to the characteristics of the jet flow and the configuration of the system. The focus of the present work is to characterize transient high speed jet flows from the differing orifice nozzle geometries and the introduction of a swirling motion into the jet flow and how this affects the characteristics of the jet flow from the reference jet flow that is free from swirling motion momentum. Another important but niche or specialised jet flow application is in reverse pulse-jet (RPJ) cleaning systems, of which is the focus application of the present work. A typical RPJ cleaning system consists of three main components: compressed air supply, valve and blowtube. The blowtube is the name given to the pipe connected to the valve and configured with a number of outlets or orifices where the flow exits into a plenum thereby entraining and inducting flow into a filter that is aligned with the orifice from which the jet flow issues. In the present work, improvements are sought from the blowtube or more specifically the exit pipe orifices for a more efficient operation of a well-designed cleaning system. The present paper will discuss and compare the flow through a number of different orifice geometries for the type flow that is typically experienced in this type of application. The operation of a single event or an actuation of the pulse-jet valve, is extremely rapid; typically approximately 300 ms. The valve is actuated and the diaphragm moves and allows the compressed air to travel from the pressure vessel or header tank through the valve past the valve seat into the blowtube and exits through plain orifices or nozzles. The extremely rapid event generates highly transient, highly turbulent free shear jet type flow from either the plain orifice or nozzle with a circular orifice geometry through which the flow exits. Advancements made by the author in subsonic flows and high-speed gas dynamic flows could provide not only improvements to the flow but further insight to the physics of high speed flows in particular around pipe exit orifices. This investigative study of the jet flow was based upon a computational analysis. It was shown that the base reference case of the jet flow that was solely a non-swirling flow although the jet flow was highly transient in nature that the centreline velocity of the jet flow had variability from the inner core to the outer extremities of the jet flow. The comparison of the base reference case with swirling jet flow will produce a longer coherent jet flow using the different orifice geometries. The stability of the jet flow was improved with the introduction of the swirling motion to the jet flow. Future developments of the transient nature of the jet flow will include experimental studies to verify the flow control methods that were used in the swirling jet flow cases.

A Fuzzy Logic in Election Sentiment Analysis: Comparison Between Fuzzy Naïve Bayes and Fuzzy Sentiment using CNN

Sentiment analysis is an analysis with an objective to identify like, dislike, comments, opinion, or feedback on certain content which will be categorized into positive, negative, or neutral. In general selection, sentiment analysis widely known to be used to predict the winner on election process. This method tries to dig the people sentiment on their governor candidates during election, whether it’s positive, negative, or neutral opinion. The output of the positive sentiment is related to people acceptance towards one of the election nominee. That statement usually applied as a base reference for determining the result of the election process. In sentiment analysis, the importance of its fuzzy logics must be considered. Each of the people statement is assumed to have the level of positive, negative, or neutral percentage. The concept of fuzzy logic is developed and applied on one of this text mining method. This research is focusing on comparison analysis and fuzzy logic application in sentiment analysis method. Two method which discussed in this research are Fuzzy Naïve Bayes and Sentiment Fuzzy with convolutional neural network. This research is applied on PILKADA of Solo and Medan district case study. The data of the people opinion are acquired from twitter and collected on September 2020 to December 2020. The two methods which mentioned before are implemented on the acquired data and the output of these method application then compared. The conclusion of this research suggest that different approach will resulting in different output.

Improved Timing for better performance of distributed data acquisition systems

Distributed data acquisition systems are the norm in the great majority of industry branches where the process to be controlled covers a physically large and often fragmented area. Many local smaller data acquisition modules are interfaced and pass raw or pre-processed data along with the timing signals. These timing signals are a vital part of data acquisition as oftentimes raw data is processed as time series and correlations are made based on timestamps. This paper presents a study for implementation of a cost-effective high precision time base (reference clock) using a GPS receiver as a primary time source and a local high precision real time clock as a secondary oscillator.

Driving Technologies for the Design of Additive Manufacturing Systems

The Additive Manufacturing (AM) technology, belonging to the most comprehensive Net Shape Forming family, has in recent years a growing trend due to the increasing quality of the built product. These results may open the application of the AM to the industrial field, moving the application from laboratories to the plant floor. This step requires machines capable of executing the technology process of AM with the requirements of the industrial environment, concerning as example the production speed, reliability, robustness, and process stability. The design of such type of machinery requires a systematic and multidisciplinary approach for reaching these industrial targets. Indeed the AM process involves several design technological issues, like temperature control of the material to be processed, characteristics of the energy source for material transition, control of the power transferred to the material, scanning system’s head control, 3D model’s layer definition, generation of the laser point’s trajectories. The final product’s quality strongly depends on all these aspects synergically linked each other, as well as on the technical solutions to realize them. The paper presents an interdisciplinary approach to the design of machines for AM, based on the Powder Bed Fusion process, and targeted to the industrial field. The technological platforms discussed in the paper are essential for such type of machines. The strategy proposed constitutes a base reference point for the definition of a methodological approach to the design of AM machinery. Doi: 10.28991/HIJ-2021-02-01-03 Full Text: PDF

An FPGA Scalable Software-Defined Radio Platform for UAS Communications Research

In the framework of modern Unmanned Aerial System (UAS) ground-board communications, a data-link system should provide with the following features [1]: multiband and adaptive modulations for responding to channel conditions changes and multi-standard interoperability, interferences resilience with a secure physical layer, incorporation of an air-to-air link complementary to the classical air-to-ground links. Varying the available communication functions to provide the above features without the need to substitute on-board components is a desired target. For this purpose, a Field Programmable Gate Aray (FPGA) scalable Software Defined Radio hardware Platform (SDRP) and its control and baseband signal processing architecture have been developed. The platform is composed by means of three boards which provide respectively the power supply, an FPGA based processing core and the radio frequency front-end. The control and baseband signal processing architecture, implemented on the FPGA, is designed with an application-independent section, working as a base reference design, and a reconfigurable section that implements communication functions and algorithms. The overall platform, at the board and FPGA architecture level, has been designed considering scalability and modularity as key features. Thanks to this platform a data-link which responds to the above target can be easily implemented. As a case study a reconfigurable data-link between a UAS and a Ground Control Station (GCS), designed to establish reliable communication in all the phases of a flight (parking, taxiing, taking off, cruising and landing), is presented.

Long periodicals in the position of permanent GNSS stations

The relevance of the study of the movements of base reference stations is determined by the task of improving the accuracy and reliability of the results of geodetic monitoring carried out using GNSS technologies. The paper presents the results of an analysis of the position of five permanent GNSS stations located in St. Petersburg for 2013-2020. Data processing by the method of precise positioning was performed using the online service CSRS-PPP. The time series were processed using the “Caterpillar”-SSA algorithm implemented in the MathCAD software package. The main attention is paid to the identification of periodic components in the movement of stations. The analysis of the series showed consistently identified periods of 3 and 12 months in the plane coordinates and 70 days and 12 months in altitude. The amplitudes of the periodicals were in the range from 1 to 10 millimeters. A trend was also identified, demonstrating a tendency for all stations to move to the northeast. The paper presents comparisons of the results obtained with previous studies.