Journal IJCRT UGC-CARE, UGCCARE( ISSN: 2320-2882 ) | UGC Approved Journal | UGC Journal | UGC CARE Journal | UGC-CARE list, New UGC-CARE Reference List, UGC CARE Journals, International Peer Reviewed Journal and Refereed Journal, ugc approved journal, UGC CARE, UGC CARE list, UGC CARE list of Journal, UGCCARE, care journal list, UGC-CARE list, New UGC-CARE Reference List, New ugc care journal list, Research Journal, Research Journal Publication, Research Paper, Low cost research journal, Free of cost paper publication in Research Journal, High impact factor journal, Journal, Research paper journal, UGC CARE journal, UGC CARE Journals, ugc care list of journal, ugc approved list, ugc approved list of journal, Follow ugc approved journal, UGC CARE Journal, ugc approved list of journal, ugc care journal, UGC CARE list, UGC-CARE, care journal, UGC-CARE list, Journal publication, ISSN approved, Research journal, research paper, research paper publication, research journal publication, high impact factor, free publication, index journal, publish paper, publish Research paper, low cost publication, ugc approved journal, UGC CARE, ugc approved list of journal, ugc care journal, UGC CARE list, UGCCARE, care journal, UGC-CARE list, New UGC-CARE Reference List, UGC CARE Journals, ugc care list of journal, ugc care list 2020, ugc care approved journal, ugc care list 2020, new ugc approved journal in 2020, ugc care list 2021, ugc approved journal in 2021, Scopus, web of Science.
How start New Journal & software Book & Thesis Publications
Submit Your Paper
Login to Author Home
Communication Guidelines

IJCRT WhatsApp Contact

  IJCRT Search Xplore - Search all paper by Paper Name , Author Name, and Title

Volume 6 | Issue 2 |

Volume 6 | Issue 2 | Month  
Downlaod After Publication
1) Table of content index in PDF
2) Table of content index in HTML 2)Table of content index in HTML
3) Front Page                     3) Front Page
4) Back Page                     4) Back Page
5) Editor Board Member 5)Editor Board Member
6) OLD Style Issue 6)OLD Style Issue
Chania Chania
IJCRT Journal front page IJCRT Journal Back Page

  Paper Title: STUDY OF SARVA SHIKSHA ABHIYAN IN THE TERMS OF COMMUNITY PARTICIPATION

  Author Name(s): Dr. Harish Kumar Singh

  Published Paper ID: - IJCRT1812831

  Register Paper ID - 186934

  Publisher Journal Name: IJPUBLICATION, IJCRT

  DOI Member ID: 10.6084/m9.doi.one.IJCRT1812831 and DOI :

  Author Country : Indian Author, --, -- , --, -- , | Research Area: Science & Technology

Published Paper URL: http://ijcrt.org/viewfull.php?&p_id=IJCRT1812831
Published Paper PDF: download.php?file=IJCRT1812831
Published Paper PDF: http://www.ijcrt.org/papers/IJCRT1812831.pdf

  Your Paper Publication Details:

  Title: STUDY OF SARVA SHIKSHA ABHIYAN IN THE TERMS OF COMMUNITY PARTICIPATION

 DOI (Digital Object Identifier) :

 Pubished in Volume: 6  | Issue: 2  | Year: April 2018

 Publisher Name : IJCRT | www.ijcrt.org | ISSN : 2320-2882

 Subject Area: Science & Technology

 Author type: Indian Author

 Pubished in Volume: 6

 Issue: 2

 Pages: 1441-1448

 Year: April 2018

 Downloads: 1512

  E-ISSN Number: 2320-2882

 Abstract

Sarva Shiksha Abhiyan (SSA) is Government of India's flagship programme for achievement of Universalization of Elementary Education (UEE) in a time bound manner, as mandated by 86th amendment to the Constitution of India making free and compulsory Education to the Children of 6-14 years age group, a Fundamental Right.In the process in 2001their was the starting of a time bound and planned national programme of SSA for univesalisation of primary education, considering the context of aims as well as expansion of SSA, the researcher has tried to make relevant study of school efforts to collect and apply the recourses in the implementation of SSA. Moreover whwt is the community participation and what is the role of parents ,member of Gram Shiksha Samitti ,teachers and educational functionaries, has also been studied by the researcher.


Licence: creative commons attribution 4.0

  License

Creative Commons Attribution 4.0 and The Open Definition

 Keywords

Study of Sarva Shiksha Abhiyan in the terms of Community Participation

  License

Creative Commons Attribution 4.0 and The Open Definition


  Paper Title: RAILWAY TRACK MONITORING SYSTEM

  Author Name(s): Pratiksha Girase, Swarali Aswale, Ankita Rout

  Published Paper ID: - IJCRT1812830

  Register Paper ID - 186749

  Publisher Journal Name: IJPUBLICATION, IJCRT

  DOI Member ID: 10.6084/m9.doi.one.IJCRT1812830 and DOI :

  Author Country : Indian Author, 400709, india , navi mumbai, india , | Research Area: Science & Technology

Published Paper URL: http://ijcrt.org/viewfull.php?&p_id=IJCRT1812830
Published Paper PDF: download.php?file=IJCRT1812830
Published Paper PDF: http://www.ijcrt.org/papers/IJCRT1812830.pdf

  Your Paper Publication Details:

  Title: RAILWAY TRACK MONITORING SYSTEM

 DOI (Digital Object Identifier) :

 Pubished in Volume: 6  | Issue: 2  | Year: April 2018

 Publisher Name : IJCRT | www.ijcrt.org | ISSN : 2320-2882

 Subject Area: Science & Technology

 Author type: Indian Author

 Pubished in Volume: 6

 Issue: 2

 Pages: 1437-1440

 Year: April 2018

 Downloads: 1396

  E-ISSN Number: 2320-2882

 Abstract

The development in the railroad area has brought about an exapnsion in the train activity thickness over the world. This has brought about the expansion in the quantity of mischances including trains.In this paper, the proposed structure incorporates a few elements which forestall train mishaps.it incorporates flame recognition ,water level recognization ,railway track split discovery, This structure makes utilization of IR sensors, fire sensor,GSM and other inserted structure Rail mischances have been expanded because of the surge streaming over the railway track.We are proposing a surge identification structure to overcome such mischances. here ,at whatever point we distinguish that there is a flood over track ,we will send a sign to the train through GSM which will stop the train furthermore send messages to higher powers of south focal railroad. In recent or in past years most of the accidents are happened due to weather conditions or not having proper balance of tracks. Automated Screening System (ASS) is used to avoid accidents. It is used to monitor traffic, Climatic conditions, it calculates distance between the tracks and strength of the track and number of gaps on tracks. Reliable compact Blue chips are used near fish plates of tacks and connected to ASS. Satellite transmission system is the medium used to transmit datafrom tracks to train and train to railway signalling system and vice versa. Track information is accessed from database and stored into ASS. If status is accurate then train will get signal to move forward. Digital siren is used to avoid level crossing accidents


Licence: creative commons attribution 4.0

  License

Creative Commons Attribution 4.0 and The Open Definition

 Keywords

ASS, Fish plates, Satellite, Sensing diodes, Antennas, Sirens.

  License

Creative Commons Attribution 4.0 and The Open Definition


  Paper Title: WIRELESS SURVEILLANCE AND SAFETY SYSTEM FOR MINE WORKERS USING ZIGBEE

  Author Name(s): Dr. S. Suryanarayana, P Prashanth Sagar, Abhijeet Kumar, A. Shiva Sai

  Published Paper ID: - IJCRT1812828

  Register Paper ID - 186655

  Publisher Journal Name: IJPUBLICATION, IJCRT

  DOI Member ID: 10.6084/m9.doi.one.IJCRT1812828 and DOI :

  Author Country : Indian Author, 500015, India , hyderabad, India , | Research Area: Science & Technology

Published Paper URL: http://ijcrt.org/viewfull.php?&p_id=IJCRT1812828
Published Paper PDF: download.php?file=IJCRT1812828
Published Paper PDF: http://www.ijcrt.org/papers/IJCRT1812828.pdf

  Your Paper Publication Details:

  Title: WIRELESS SURVEILLANCE AND SAFETY SYSTEM FOR MINE WORKERS USING ZIGBEE

 DOI (Digital Object Identifier) :

 Pubished in Volume: 6  | Issue: 2  | Year: April 2018

 Publisher Name : IJCRT | www.ijcrt.org | ISSN : 2320-2882

 Subject Area: Science & Technology

 Author type: Indian Author

 Pubished in Volume: 6

 Issue: 2

 Pages: 1420-1427

 Year: April 2018

 Downloads: 1323

  E-ISSN Number: 2320-2882

 Abstract

Mining safety is one of the major concerns over the many decades. The loss of human health resources increasing as mining progress. The proper channel of communication in the mines was not established till now. They still using old, wired telephonic communication for the purpose of communication to the base station which leads to loss manpower sometime. This project addresses a cost-effective, flexible solution of underground mine workers safety and established faithful communication system inside the underground mines.


Licence: creative commons attribution 4.0

  License

Creative Commons Attribution 4.0 and The Open Definition

 Keywords

Arduino Uno, ZigBee, LM35, MQ2, DHT11

  License

Creative Commons Attribution 4.0 and The Open Definition


  Paper Title: AN OVERVIEW OF HOW THE SENSING TECHNOLOGY IS USED IN ACCIDENTS DETECTION, GARBAGE COLLECTION AND AMBULANCE CLEARANCE

  Author Name(s): Charan Tej S J, Vikranth B M, Abishek M K, Abijith Chauhan

  Published Paper ID: - IJCRT1812827

  Register Paper ID - 186422

  Publisher Journal Name: IJPUBLICATION, IJCRT

  DOI Member ID: 10.6084/m9.doi.one.IJCRT1812827 and DOI :

  Author Country : Indian Author, 560085, India , Bangalore, India , | Research Area: Science & Technology

Published Paper URL: http://ijcrt.org/viewfull.php?&p_id=IJCRT1812827
Published Paper PDF: download.php?file=IJCRT1812827
Published Paper PDF: http://www.ijcrt.org/papers/IJCRT1812827.pdf

  Your Paper Publication Details:

  Title: AN OVERVIEW OF HOW THE SENSING TECHNOLOGY IS USED IN ACCIDENTS DETECTION, GARBAGE COLLECTION AND AMBULANCE CLEARANCE

 DOI (Digital Object Identifier) :

 Pubished in Volume: 6  | Issue: 2  | Year: April 2018

 Publisher Name : IJCRT | www.ijcrt.org | ISSN : 2320-2882

 Subject Area: Science & Technology

 Author type: Indian Author

 Pubished in Volume: 6

 Issue: 2

 Pages: 1413-1419

 Year: April 2018

 Downloads: 1276

  E-ISSN Number: 2320-2882

 Abstract

The Rapid growth of technology and infrastructure has made our lives easier. The developing urban area that create sustainable economic development and high quality of life by excelling in multiple key areas; Economic, mobility, environment, people, living. Excelling in these key areas can be done so through strong ICT infrastructure.it is observed that the advent of technology has also increased the traffic hazards and the road accidents takes place frequently which causes huge loss of life and property because of the poor emergency facilities. This paper will provide an optimum solution to this draw back. This paper contains three parts in which the first part illustrates about how accidents are being detected using the vibrators. Nowadays certain actions are taken to improve the level of cleanliness in the country. People are getting more active in doing all the things possible to clean their surroundings. Thus, the second part illustrates how the waste is managed using the ultrasonic sensors. The third part illustrates about how an attempt is made to solve the problem of ambulance clearance. The whole concept of this paper is about contributing towards making the city smarter, thus, making our country smarter.


Licence: creative commons attribution 4.0

  License

Creative Commons Attribution 4.0 and The Open Definition

 Keywords

Ultrasonic sensors, vibrators, GSM, GPS, Arduino, Wi-Fi Module

  License

Creative Commons Attribution 4.0 and The Open Definition


  Paper Title: A REVIEW ON USE OF SOCIAL NETWORKING SITES BY ACADEMICIANS AND RESEARCHERS

  Author Name(s): Prof. PRATIBHA KULKARNI P.E.S.Modern College of Engineering, Dr.Poornashankar

  Published Paper ID: - IJCRT1812826

  Register Paper ID - 186414

  Publisher Journal Name: IJPUBLICATION, IJCRT

  DOI Member ID: 10.6084/m9.doi.one.IJCRT1812826 and DOI :

  Author Country : Indian Author, India, India , Pune, India , | Research Area: Management

Published Paper URL: http://ijcrt.org/viewfull.php?&p_id=IJCRT1812826
Published Paper PDF: download.php?file=IJCRT1812826
Published Paper PDF: http://www.ijcrt.org/papers/IJCRT1812826.pdf

  Your Paper Publication Details:

  Title: A REVIEW ON USE OF SOCIAL NETWORKING SITES BY ACADEMICIANS AND RESEARCHERS

 DOI (Digital Object Identifier) :

 Pubished in Volume: 6  | Issue: 2  | Year: April 2018

 Publisher Name : IJCRT | www.ijcrt.org | ISSN : 2320-2882

 Subject Area: Management

 Author type: Indian Author

 Pubished in Volume: 6

 Issue: 2

 Pages: 1408-1412

 Year: April 2018

 Downloads: 1398

  E-ISSN Number: 2320-2882

 Abstract


Licence: creative commons attribution 4.0

  License

Creative Commons Attribution 4.0 and The Open Definition

 Keywords

Academicians, Academic SNS, SNS Researchers.

  License

Creative Commons Attribution 4.0 and The Open Definition


  Paper Title: SMART CITY

  Author Name(s): RAMESHA N G

  Published Paper ID: - IJCRT1812825

  Register Paper ID - 185743

  Publisher Journal Name: IJPUBLICATION, IJCRT

  DOI Member ID: 10.6084/m9.doi.one.IJCRT1812825 and DOI :

  Author Country : Indian Author, 577516, India , Davangere, India , | Research Area: Arts

Published Paper URL: http://ijcrt.org/viewfull.php?&p_id=IJCRT1812825
Published Paper PDF: download.php?file=IJCRT1812825
Published Paper PDF: http://www.ijcrt.org/papers/IJCRT1812825.pdf

  Your Paper Publication Details:

  Title: SMART CITY

 DOI (Digital Object Identifier) :

 Pubished in Volume: 6  | Issue: 2  | Year: April 2018

 Publisher Name : IJCRT | www.ijcrt.org | ISSN : 2320-2882

 Subject Area: Arts

 Author type: Indian Author

 Pubished in Volume: 6

 Issue: 2

 Pages: 1406-1407

 Year: April 2018

 Downloads: 1281

  E-ISSN Number: 2320-2882

 Abstract

Smart city is an initiative launched by the Government of India to encourage national, as well as multi-national companies to manufacture their products in India. It was launched by Prime Minister Narendra Modi on 25 September 2014. India emerged, after initiation of the programmed in 2015, as the top destination globally for foreign direct investment(FDI), surpassing the United States of America as well as the People's Republic of China. In 2015, India received US$63 billion in FDI.


Licence: creative commons attribution 4.0

  License

Creative Commons Attribution 4.0 and The Open Definition

 Keywords

FDI, People's Republic of China

  License

Creative Commons Attribution 4.0 and The Open Definition


  Paper Title: INNOVATIVE AGRICULTURE APPLICATION FOR MAXIMIZING PROFIT OF ALLIED BUSINESS

  Author Name(s): Pooja N. Balchetty, Priyanka Nanaware, Trupti Suryavanshi, Vidya Shitole

  Published Paper ID: - IJCRT1812824

  Register Paper ID - 185085

  Publisher Journal Name: IJPUBLICATION, IJCRT

  DOI Member ID: 10.6084/m9.doi.one.IJCRT1812824 and DOI :

  Author Country : Indian Author, 410401, India , Pune, India , | Research Area: Science & Technology

Published Paper URL: http://ijcrt.org/viewfull.php?&p_id=IJCRT1812824
Published Paper PDF: download.php?file=IJCRT1812824
Published Paper PDF: http://www.ijcrt.org/papers/IJCRT1812824.pdf

  Your Paper Publication Details:

  Title: INNOVATIVE AGRICULTURE APPLICATION FOR MAXIMIZING PROFIT OF ALLIED BUSINESS

 DOI (Digital Object Identifier) :

 Pubished in Volume: 6  | Issue: 2  | Year: April 2018

 Publisher Name : IJCRT | www.ijcrt.org | ISSN : 2320-2882

 Subject Area: Science & Technology

 Author type: Indian Author

 Pubished in Volume: 6

 Issue: 2

 Pages: 1393-1405

 Year: April 2018

 Downloads: 1307

  E-ISSN Number: 2320-2882

 Abstract

The agriculture Project's objective is to increase rural income and simulate the rural economy through rural entrepreneurship. To achieve these objectives, the project focuses on improving factor productivity and competitiveness of agricultural products by providing assistance for the: : a) privatization of rural lands; b) improvement of human resources skills for entrepreneurship in rural areas; c) introduction of new farming technologies consistent with transformed private agriculture; and d) improvement in food quality. Project components include: i) Goat Farming; ii) Apiculture; iii) Cashew Processing.


Licence: creative commons attribution 4.0

  License

Creative Commons Attribution 4.0 and The Open Definition

 Keywords

Monitoring, Databases, Information management Fodder & Supplier Management, Apiculture.

  License

Creative Commons Attribution 4.0 and The Open Definition


  Paper Title: SIMULATION AND ANALYSIS OF EFFICIENT MULTILEVEL INVERTER FOR SOLAR PANEL

  Author Name(s): Dhruvkumar P. Patel, Prof. Trunal k. Patel

  Published Paper ID: - IJCRT1812823

  Register Paper ID - 187869

  Publisher Journal Name: IJPUBLICATION, IJCRT

  DOI Member ID: 10.6084/m9.doi.one.IJCRT1812823 and DOI :

  Author Country : Indian Author, 384002, INDIA , Mehsana, INDIA , | Research Area: Science & Technology

Published Paper URL: http://ijcrt.org/viewfull.php?&p_id=IJCRT1812823
Published Paper PDF: download.php?file=IJCRT1812823
Published Paper PDF: http://www.ijcrt.org/papers/IJCRT1812823.pdf

  Your Paper Publication Details:

  Title: SIMULATION AND ANALYSIS OF EFFICIENT MULTILEVEL INVERTER FOR SOLAR PANEL

 DOI (Digital Object Identifier) :

 Pubished in Volume: 6  | Issue: 2  | Year: April 2018

 Publisher Name : IJCRT | www.ijcrt.org | ISSN : 2320-2882

 Subject Area: Science & Technology

 Author type: Indian Author

 Pubished in Volume: 6

 Issue: 2

 Pages: 1385-1392

 Year: April 2018

 Downloads: 1270

  E-ISSN Number: 2320-2882

 Abstract

In recent years, multilevel inverters have gained more attention for high power applications. A multilevel inverter not only achieves high power ratings, but also enables the use of renewable energy sources. Single phase inverter is widely used for stand-alone systems and micro-grid application. The major limitation faced by multilevel inverters are, number of switches required large which leads to higher switching losses. There are many limitations in extracting power from renewable energy resources. To minimize the power demand and scarcity we have to improve the power extracting methods. Multilevel inverter can be used to extract power from solar cells. In these paper we work on design cascade (5 type, 7 type) multilevel inverter for increase performance of existing system and apply on grid with solar panel. It synthesizes the desired ac output waveform from several dc sources. The main objective of this paper is to study the 5-level and 7-level Cascaded Multilevel Inverter. In this paper the different parameters like voltage, current, THD in 5-level and 7-level Cascaded Multilevel Inverter and analysis on solar panel.


Licence: creative commons attribution 4.0

  License

Creative Commons Attribution 4.0 and The Open Definition

 Keywords

Solar Panel, Multilevel Inverter, PWM Control, Renewable energy

  License

Creative Commons Attribution 4.0 and The Open Definition


  Paper Title: Detection of Human Stress using Short Term ECG and HRV Signals

  Author Name(s): ANAS KHAN, AKHLAQUE AHMAD KHAN, QAMAR ALAM

  Published Paper ID: - IJCRT1812822

  Register Paper ID - 187817

  Publisher Journal Name: IJPUBLICATION, IJCRT

  DOI Member ID: 10.6084/m9.doi.one.IJCRT1812822 and DOI :

  Author Country : Indian Author, 226016, INDIA , LUCKNOW, INDIA , | Research Area: Science & Technology

Published Paper URL: http://ijcrt.org/viewfull.php?&p_id=IJCRT1812822
Published Paper PDF: download.php?file=IJCRT1812822
Published Paper PDF: http://www.ijcrt.org/papers/IJCRT1812822.pdf

  Your Paper Publication Details:

  Title: DETECTION OF HUMAN STRESS USING SHORT TERM ECG AND HRV SIGNALS

 DOI (Digital Object Identifier) :

 Pubished in Volume: 6  | Issue: 2  | Year: April 2018

 Publisher Name : IJCRT | www.ijcrt.org | ISSN : 2320-2882

 Subject Area: Science & Technology

 Author type: Indian Author

 Pubished in Volume: 6

 Issue: 2

 Pages: 1381-1384

 Year: April 2018

 Downloads: 1327

  E-ISSN Number: 2320-2882

 Abstract

The paper reflects upon the issue of human stress detection using Electrocardiogram (ECG) and Heart Rate Variability (HRV) signals. This includes pre-processing of ECG signal, HRV signal extraction, feature selection and their classification. Pre-processing includes removal of power line interference, baseline wander etc. from the raw ECG. Pan-Tompkins algorithm is used for extraction HRV signal from ECG signal.The ECG is classified as stress or normal by setting appropriate threshold value. Short term ECG needed for stress detection produces a reliable output of great accuracy.


Licence: creative commons attribution 4.0

  License

Creative Commons Attribution 4.0 and The Open Definition

 Keywords

HRV signal, Pan Tompkins algorithm, ECG,ANS

  License

Creative Commons Attribution 4.0 and The Open Definition


  Paper Title: AUTOMATIC IRRIGATION AND ALERTING SYSTEM USING ARDUINO UNO

  Author Name(s): Saravanan T Y, G Revathi, G Satheesh, S Dhanush, G Himakar

  Published Paper ID: - IJCRT1812821

  Register Paper ID - 187815

  Publisher Journal Name: IJPUBLICATION, IJCRT

  DOI Member ID: 10.6084/m9.doi.one.IJCRT1812821 and DOI :

  Author Country : Indian Author, 524101, India , Gudur, India , | Research Area: Science & Technology

Published Paper URL: http://ijcrt.org/viewfull.php?&p_id=IJCRT1812821
Published Paper PDF: download.php?file=IJCRT1812821
Published Paper PDF: http://www.ijcrt.org/papers/IJCRT1812821.pdf

  Your Paper Publication Details:

  Title: AUTOMATIC IRRIGATION AND ALERTING SYSTEM USING ARDUINO UNO

 DOI (Digital Object Identifier) :

 Pubished in Volume: 6  | Issue: 2  | Year: April 2018

 Publisher Name : IJCRT | www.ijcrt.org | ISSN : 2320-2882

 Subject Area: Science & Technology

 Author type: Indian Author

 Pubished in Volume: 6

 Issue: 2

 Pages: 1376-1380

 Year: April 2018

 Downloads: 1320

  E-ISSN Number: 2320-2882

 Abstract


Licence: creative commons attribution 4.0

  License

Creative Commons Attribution 4.0 and The Open Definition

 Keywords

ARDUINO MICROCONTROLLER, SENSORS, LCD DISPLAY, GSM MODULE

  License

Creative Commons Attribution 4.0 and The Open Definition



Call For Paper September 2026
Indexing Partner
ISSN and 7.97 Impact Factor Details


ISSN
ISSN
ISSN: 2320-2882
Impact Factor: 7.97 and ISSN APPROVED
Journal Starting Year (ESTD) : 2013
ISSN
ISSN and 7.97 Impact Factor Details


ISSN
ISSN
ISSN: 2320-2882
Impact Factor: 7.97 and ISSN APPROVED
Journal Starting Year (ESTD) : 2013
ISSN
DOI Details

Providing A digital object identifier by DOI.org How to get DOI?
For Reviewer /Referral (RMS) Earn 500 per paper
Our Social Link
Open Access
This material is Open Knowledge
This material is Open Data
This material is Open Content
Indexing Partner

Scholarly open access journals, Peer-reviewed, and Refereed Journals, Impact factor 7.97 (Calculate by google scholar and Semantic Scholar | AI-Powered Research Tool) , Multidisciplinary, Monthly, Indexing in all major database & Metadata, Citation Generator, Digital Object Identifier(DOI)

indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer
indexer