UAS Missions and their Respective Attributes, Challenges, and Legalities

            There are many missions that unmanned aerospace systems (UASs) accomplish in both the public and civil realms. One of the most well suited missions to UAS is aerial Intelligence, Surveillance, and Reconnaissance (ISR). This mission set it not only a military mission, it is also conducted by police, border patrol, and FBI. All agencies that conduct aerial ISR via UAS share many of the same tactics techniques and procedures to accomplish the task. The type, size, and design of the UASs used in this mission vary widely based on where the mission is being conducted, the budget that a particular agency has for the mission, as well as other mission related constraints that are unique to each agency.     

            Three examples of platforms that accomplish the role of aerial ISR are the MQ-1C Gray Eagle which is used by the US Army, the MQ-8 Fire Scout which is used by the US Navy, and the Qube which was used by the Grand Forks, ND Police department to make its first night time arrest aided by a UAS (Koebler, 2014). The MQ-1C is a standard large fuel powered fixed wing UAS designed for launch and recovery via a 5,000ft runway. The Gray Eagle is capable of flying beyond line of sight as well as loitering for over 25 hours. This long loiter time and extended range provide the US Army with a powerful and capable system for aerial ISR (GA-ASI, 2016). 

The MQ-8 Fire Scout is used by the US Navy to conduct aerial ISR, but it is a rotary wing platform which aids in launch and recovery from ships and boats. The system is capable of flight up to 16,000ft as well as can loiter for over 12 hours. While not as capable as the Gray Eagle, the Fire Scout has the huge advantage of vertical takeoff and landing, which is vital when operating at sea (Northrup Grumman Inc., 2016). 

The Qube by AeroVironoment is a small battery powered quadcopter UAS that is utilized by the Grand Forks, ND police department to aid in criminal surveillance, which is the police version of ISR. The Qube is capable of only 40 minutes of flight and has a line of sight range of only 1km, but meets both the mission requirements and budgetary constraints of a small police department (AeroVironment Inc., 2016).

            The mission requirements vary depending on where and when the mission takes place, but there are some major considerations that must be taken in to account when selecting a UAS platform. Most aerial ISR systems need to be able to gain a vantage point that humans cannot typical achieve on foot. This means that they need to be well above the target. For high value targets in Afghanistan it could mean 20,000ft loiter altitude. For a ship or marine target, 10,000ft above the ocean may be the right solution. For a police chase in an urban area, a 400ft altitude could be adequate. The other main mission task that must be executed is relaying the video photography of the target back to the operator in near real time. Regardless of size, platform type, or cost, this function is accomplished at all levels for aerial ISR UASs.

            The major challenges for conducting aerial ISR can be two fold, there are platform based challenges as well as payload based challenges. In terms of platform challenges, achieving beyond line of sight flight is expensive and technologically advanced. The use of third party satellites is expensive as well as complex. Another aspect of flying beyond line of sight domestically is that is regulatory restrictive (Anderson, 2016). One Major benefit of utilizing UASs for aerial ISR is that they can remain in the air longer than most other manned platforms. Compared to systems like the MQ-12 Liberty manned airplane that is flown by the US Air Force, most UASs regardless of size can outlast it while conducting an ISR mission. The MQ-12 can only stay aloft for 6 hours without having to break station to refuel (Airforcetechnology.com, 2016). The MQ-1C can last a full 25 hours on one tank of fuel (GA-ASI, 2016).

            There are multiple legal and moral issues that often are challenging for UAS to be utilized in aerial ISR mission, and even more so when UASs are equipped with munitions such as the hellfire missile. In the case of a military UAS conducting ISR and firing hellfires there is a moral issue as to who is to blame in case of collateral damage cause by improper target identification, or lack of target area situational awareness (McGuire, 2015). There are major legal issues when conducting ISR domestically by the police. The main issue is privacy. Privacy is a huge concern for the American public, and when conducting police action, the use of a UAS could require a warrant depending the state. California is a very conservative state when it comes to UAS use by the police. Recently the state assembly approved a law requiring police to get a warrant to use a UAS to conduct a search (Bailey, 2014). Other states are working through litigation to determine the legality of UAS surveillance by police, but there are many challenges both perceived and actual to utilizing UASs for aerial ISR both domestically and deployed.       

References

AeroVironment Inc. (2016). Visit AeroVironment Inc. Retrieved October 18, 2016, from https://www.avinc.com/uas/view/qube

Anderson, R. (2016, September 24). The opportunities and challenges of flying drones beyond line of sight (BLOS) | Commercial Drones Blog | Aviassist. Retrieved October 18, 2016, from http://www.aviassist.com.au/commercial-drones-blog/opportunities-challenges-flying-drones-beyond-line-sight-blos/

Bailey, R. (2014, August 05). California Assembly Passes Bill Requiring Police to Get a Warrant for Surveillance Drones. Retrieved October 18, 2016, from http://reason.com/blog/2014/08/05/california-assembly-passes-legislation-r

GA-ASI. (2016). Gray Eagle UAS. Retrieved October 18, 2016, from http://www.ga-asi.com/gray-eagle

Koebler, J. (2014, October 2). Police Used a Drone to Chase Down and Arrest Four DUI Suspects in a Cornfield. Retrieved October 18, 2016, from http://motherboard.vice.com/read/police-used-a-drone-to-chase-down-and-arrest-four-dui-suspects-in-a-cornfield

Maguire, L. (2015, September 26). The Ethics of Drone Warfare. Retrieved October 18, 2016, from http://www.philosophytalk.org/community/blog/laura-maguire/2015/09/ethics-drone-warfare

Northrup Grumman Inc. (2016). Fire Scout. Retrieved October 18, 2016, from http://www.northropgrumman.com/Capabilities/FireScout/Pages/default.aspx?utm_source=PrintAd

Unmanned Aerial Systems in National Airspace

     Unmanned aircraft are a vital asset in today’s world. They have made aerial photography and videography cheaper and more accessible to both hobbyists and small business owners.
Today, the major hurtle is UAS integration into national airspace (NAS). One of the major aspects to integration of UAS into NAS is the ability for systems to sense and avoid other aircraft or obstacles. In the current FAA regulations, the term “see and avoid” exist, but in the future “sense and avoid” will be applied (Carey, 2013). Until that point UASs are unable to comply with the requirements, but this has not stopped companies and the military from working towards smart solutions to the providing a sense and avoid system that are dependable enough to garner FAA approval and support.

     The techniques for monitoring separation from both manned and unmanned systems come in multiple forms. The overarching concept, regardless of technique, is that the UAS is informed of nearby traffic and can execute a predictable solution that will provide regulatory separation. The two major techniques to gathering this traffic information can be categorized as ground based or airborne based sensing. Ground based sensing utilize radar systems similar to air traffic control agencies. The major difference is that these radar systems integrate directly into the ground control station (GCS) of the UAS (SRC Inc. 2016). The airborne technique relies on advanced sensors being equipped directly on the air vehicle portion of the UAS. A lot of research is going into the development of micro radar systems that would be able to fit a highly capable radar system into a very small package (Gorwara, 2014).
 
     Some of the major considerations that need to be factored in when deciding between ground based sensing or airborne sensing needs to be attributed to both the size and type of UAS airframe in questions. Small UASs need to be very cognizant of size power and weight of any additional sensors that need to be added to the air vehicle. These systems may benefit from a ground based system that is able to communicate with the ground control station. Additionally, micro radar systems are being produced to provide small quadcopter sized UASs with a robust ability to sense and avoid traffic with light weight and low power solutions (Gorwara, 2014).  Large UASs like military grade UASs have a large payload capacity and a large power source capable of both carrying and powering complex sensors that can provide adequate sense and avoid capabilities. Another aspect to consider is the type of airframe in question. A small quadcopter may move slowly and within a relatively small range. This means less powerful sensors could be used to provide the separation and spacing required. Large fast fixed wing system could fly at high altitudes and at high speeds with an enormous range, so providing powerful onboard solutions may make the most sense.

     Some larger systems like the MQ-4 global hawk actually have terminal collision and avoidance system (TCAS) which is used on most large commercial manned aircraft. There is also research into a new system call Airborne Collision Avoidance System for Unmanned Aircraft or ACAS Xu for short. This system will integrate with TCAS as well as provide autonomous functions that will support proper sense and avoid decision making if the UAS has lost link or is in autonomous flight (NASA, 2015).
 
     Another current initiative is the use of a system called the ground based sense and avoid system (GBSAA) by SRC Inc. This system is currently being installed by the US Army at posts that are hubs for large UAS training. Fort Hood and Fort Campbell are both test beds for this technology (Mishory, 2016). The system utilizes powerful and expensive ground based radar dishes to directly communicate any traffic advisories directly to the GCS of the UASs operating within its area of responsibility. This system can detect both manned and unmanned aircraft as well as other airborne obstacles. The benefits of this system are that just one GBSAA can provide coverage for multiple aircraft working in a defined area. Also, GBSAA does not add any additional power or weight requirements to the actual air vehicles that are utilizing its information (SRC Inc., 2016).

     Regardless to size and type, the need for FAA approved sense and avoid systems is vital to the integration of UAS into NAS. By understanding the limitations and capabilities associated with the size and type of a UAS will help engineers provide the best solution to each system on a case by case basis. The need to ensure the right capability is equipped on the right system is also vital in reducing excess costs and ensuring the general UAS user base is capable and willing to equip their UASs with these systems when it becomes available.  Additionally, integrating the UAS sense and avoid technology into manned sense and avoid systems like TCAS will be vital to future integration.      

 References
Carey, B. (2013, June 22). FAA Plans Unmanned 'Sense and Avoid' Rule in 2016. Retrieved
October 03, 2016, from http://www.ainonline.com/aviation-news/air-transport/2013-07-22/faa-plans-unmanned-sense-and-avoid-rule-2016

Gorwara, A. (2014). Doppler micro sense and avoid radar. Retrieved October 3, 2016, from http://pmi-rf.com/documents/DopplerMicroSenseandAvoidRadarPaper.pdf

Mishory, J. (2016, June 16). Initial UAS flights using GBSAA system at Ft. Hood have been delayed. Retrieved October 03, 2016, from https://insidedefense.com/daily-news/initial-uas-flights-using-gbsaa-system-ft-hood-have-been-delayed

NASA. (2015, January 25). NASA, FAA, Industry Conduct Initial Sense-and-Avoid Test. Retrieved October 03, 2016, from http://www.nasa.gov/centers/armstrong/Features/acas_xu_paves_the_way.html

SRC Inc. (2016). Ground-Based Sense and Avoid Radar System. Retrieved October 03, 2016, from http://www.srcinc.com/what-we-do/radar-and-sensors/gbsaa-radar-system.html

Activity 2-4: Weeding Out a Solution

Scenario

A UAS is to be designed for precision crop-dusting. In the middle of the design process, the system is found to be overweight.

•         Two subsystems – 1) Guidance, Navigation & Control [flying correctly] and 2) Payload delivery [spraying correctly] have attempted to save costs by purchasing off-the-shelf hardware, rather than a custom design, resulting in both going over their originally allotted weight budgets. Each team has suggested that the OTHER team reduce weight to compensate.

•         The UAS will not be able to carry sufficient weight to spread the specified (Marketing has already talked this up to customers) amount of fertilizer over the specified area without cutting into the fuel margin. The safety engineers are uncomfortable with the idea of changing the fuel margin at all.

Write a response describing how you, as the Systems Engineer, would go about resolving this issue. Use your imagination, and try to capture what you would really do. Take into account and express in your writing the things you’ve learned so far in this module: What are your considerations? What are your priorities? What do you think about the future prospects for the “next generation, enhanced” version of the system as a result of your approach?

Solution

In regards to the scenario above, there are multiple responsibilities that I would have as the systems engineer responsible for resolving the issue between the guidance, navigation and control team and the payload delivery team. The three overarching roles that an ideal systems engineer must assume are; intermediary between design teams, the decision maker when conflicts occur between teams’ and final authority on whether a is ready to hand off to the costumer. Within each role, I must also examine and understand the requirements set forth by the customer, provide clear and concise communication between design teams, and be prepared to take charge of the project as a whole to ensure its on time, well designed, and meets expectations (Embry Riddle Aeronautical University, 2015). Below I have outlined how I would resolve to current issue by analyzing and describing how I would accomplish each one of my three overarching responsibilities.

Systems Engineer as an Intermediary

            As the systems engineer I would recognize that the two design teams that are arguing are responsible for very different systems that require very unique technical knowledge to accomplish. The skills associated with developing guidance and navigation are very technical with much of the detail in sensors and computer coding. The payload delivery design team would be more focused on the mechanical aspect of the project. The Payload design team may also feel a certain level of self-proclaimed importance due to the fact that the entire project is essentially built to perform the single task that they are reasonable for. It’s this understanding of not only the requirements and project, but it’s the interpersonal skills and understanding of the design teams as people that could help me perform my duties as an intermediary. I would work to educate both design teams as to how important the other teams contribution to the total project is and perhaps encourage them to take a minute and put themselves in the others shoes. Here we could pass ideas between the design teams and ensure both teams have a good understanding of how far they should be willing to flex in order to ensure the project completion stays the main focus. Perhaps this alone would invigorate one or both teams to seek smart and cost effective solutions to reduce weight from their respective components. 

Systems Engineer as the Decision Maker

            If acting as the intermediary failed to result in a constructive resolution to the overweight problem between both design teams, I would have to utilize the decision making responsibility of my job to seek resolution to the conflict. In general, I would have to take a very detailed look at both the requirements and the costs associated with each design teams’ components and determine for the teams how they would resolve the conflict. I would have to have enough technically knowledge of both subsystems in order to make smart and well educated decisions (System engineer vs. system architect, 2011, p. 73 sec.). Perhaps I could utilize my knowledge of the system as a whole to help both design teams work a creative solution that would lower the weight of both components. Perhaps the off the shelf systems that both teams used contained their own power control unit, but the design team associated with power control told me that they would be able to handle the power control requirements of each of the subsystems in question and both teams would be able to reduce the weight of the system through this efficiency. I would tell both teams to integrate into the main power control unit and then the conflict would be resolved. This example not only demonstrates my role as decision maker, but also reinforces my role as intermediary between design teams at the same time.

Systems Engineer as the Final Authority

            In regards to the above scenario, my role as final authority ties into all other aspects of my job as systems engineer due to the fact that my adherence to satisfying the original requirements is what sparked the conflict in the first place. If I did not take my role as the final authority seriously, I may have aloud to teams to continue forward with their current and produce a final product that was not capable of what it was advertised to do. This would hinder both current and future sales potential.

            The above responsibilities often run concurrently and continually while performing duties as a systems engineer therefore it’s essential to continually relook the requirements and current technology in order to stay one step ahead of the design process. Looking at the iterative design process, the systems engineer is in the best position to fuse future technologies into the project for the next version of the system. Perhaps in the future, a light weight navigation computer may become cheaper and therefore relieve the weight issue. On the other hand, I could reduce the allowed weight of both design teams and increase the payload capability which could make our product better than the competition. Another option would be to keep weight requirements and payload capacity the same while decreasing system cost for future iterations. A systems engineer should balance cost, performance, and capability when looking forward to future versions of systems in order to ensure relevancy in the current and future markets (Dahmann, n.d).     

References

Dahmann, J. (n.d.). A Model of Systems Engineering in a System of Systems Context. Retrieved September 19, 2016, from http://www.acq.osd.mil/se/docs/2008-04-04_CSER-Paper_Dahmann-etal-SoS.pdf  

Embry Riddle Aeronautical University. (2015). ASCI-530 unmanned systems: Module 2 - Global system design concepts, requirements and specification overview.

System engineer vs. system architect (2011). [Motion Picture]. Retrieved Sept 19, 2016, from

https://www.youtube.com/watch?v=wWnESjf4ajQ

The TDR-1 (1943) vs The MQ-1C (2016)

     One of the oldest UASs that utilizes a video camera and had the ability to drop ordinance is the TDR-1. In 1943 the US Navy worked with both the RCA television company and the Interstate Engineer Company to produce the TDR-1. This aircraft was made out of plywood and tubular steel and weight in at over 5,900 pounds (not including munitions). The aircraft was capable of flying over 495 NM in a single mission and could carry a 2000 pound bomb or torpedo. The radio control system and RCA television camera could be broadcasted about 8 miles to either a ground control station or a flying mothership. Considering TVs and radio controlled systems were just being invented around this time, it was an extremely cutting edge system that proved to be a capable system in combat. In 1945 the TDR-1 actually saw real combat and took out an enemy ship off the cost of the Russel Islands (Newport News Ship Building Inc., n.d.). Looking at UASs of today this system can be compared to the MQ-1C Gray Eagle due to their similarities and methodologies.

The TDR-1 Assault Drone

Similarities

            The TDR-1 and the MQ-1C both utilize video capture as a form of munition guidance and target acquisition. Both systems utilize a ground control station and portions of the electromagnetic spectrum to control both the aircraft itself and the munitions they carry. Both were fixed wing platforms and both had quite a good mission endurance range. The TDR-1 could carry over 2000 pounds of either bomb or torpedo and the MQ-1C can carry 400 pounds of precision guided munitions (GA-ASI Inc., 2016). These major broad stroke concepts are near mirror images, but upon further investigation one can see that much of the technology equipped on the MQ-1C has truly evolved dramatically since 1943. Many of the sub systems that have evolved did not only evolved for the UAS industry, but can attribute their evolution to the computer evolution, the camera evolution, and aeronautical evolution that has taken place since 1943.

The MQ-1C Gray Eagle 

Differences

            Some of the major differences has to do with the fact that integrated circuits did not exist until 1958 (TI Inc., 2008). Much of the computing was accomplished by vacuum tubes. This limited command and control to very simple techniques. Setting the altitude for the TDR-1 was done through dialing a rotary phone dial and have each number represent a particular altitude above ground level (Newport News Ship Building Inc., n.d.). As global navigation techniques evolved into GPS and INS sensors, the idea of following a UAS with a mothership or using just line of sight to figure out where it is became obsolete. The MQ-1C is equipped with redundant GPSs and INSs in order to ensure the operator knows exactly where the system is even when operating via satellites beyond line of sight (GA-ASI., 2016). Another major difference between the TDR-1 and the MQ-1C is that the MQ-1C utilizes digital communication technology. Along with an advancements in camera technology, the swap to digital communication methods allowed for much higher bandwidth communication as well as much further communication distances to include beyond line of sight.

The Future

            Looking even further into the future and taking notes from what we have seen evolved since 1943, one can see there is a bright future of UAS technology. Some of the major initiatives in the department of defense have to deal with simplification and automation of unmanned systems in general. Taking the need for highly skilled operators, and huge logistic supply chains out of the equation is one of the most vital aspects of future success of many of the current UAS programs. Much of these goals will be accomplished through standardizing future technologies, creating modular payload and interoperability with both manned and other unmanned systems (Department of Defense, 2013).   

References:

Department of Defense. (2013). Unmanned Systems Integrated Road Map FY 2013-FY2038. Retrieved September 13, 2016, from http://www.defense.gov/Portals/1/Documents/pubs/DOD-USRM-2013.pdf

GA-ASI Inc. (2016). Gray Eagle UAS. Retrieved September 13, 2016, from http://www.ga-asi.com/gray-eagle

Newport News Ship Building Inc. (n.d.). TDR-1: First Operational US Navy Drone... Successful in Combat in 1944! Retrieved September 12, 2016, from http://www.nnapprentice.com/alumni/letter/TDR_1.pdf   

TI Inc. (2008). Texas Instruments - 1958 Jack Kilby invents integrated circuit. Retrieved September 13, 2016, from http://www.ti.com/corp/docs/company/history/timeline/semicon/1950/docs/58ic_kilby.htm

    

US Army. (2016). MQ-1C Gray Eagle Unmanned Aircraft System (UAS). Retrieved September 13, 2016, from http://asc.army.mil/web/portfolio-item/aviation_gray-eagle-uas/

Bluefin-21’s Sensors and Advances in Maritime Sensors

By Brett Chereskin

Abstract

This paper provides an explanation of the sensors and capabilities of the Bluefin-21 autonomous underwater vehicle (AUV). There are four topics address within this paper. The first is an analysis of marine sensors that support underwater search and rescue. The second topic proposes modification to the AUV that would increase search and rescue capability. The third topic proposes possible sea to air unmanned system coordination, and the final topic weighs the pros and cons between manned and unmanned systems in maritime sensor technology.  

Introduction

The Bluefin-21 is an autonomous underwater vehicle (AUV) that is build by Bluefin Robotix. This advanced maritime AUV has recently been used in the search for Malaysia Airline flight MH370 and contains many sensors that are perfectly suited to the underwater search and rescue mission (Chand, 2014). Understanding the available sensors used on the Bluefin-21 will help determine if any modification can be made that will increase it’s capabilities as well as if integrating with unmanned aerial systems (UASs) could provide an increase to its mission success. Additionally, by analyzing the advantages of sensors suited to unmanned systems a clear understanding of this topic will be gained.       

The Sensors of Bluefin-21

The Bluefin-21 can be fitted with multiple sensors depending on the mission requirement. One of the most commonly used sensors for maritime search and rescue on the Bluefin-21 is the EdgeTech 2200-M 120/410 kHz side scan sonar (Chand, 2014). The EdgeTech 2200-M gathers side scan and/or sub-bottom data using EdgeTech’s proprietary technology in water depths up to 6000 meters (EdgeTech, 2015).  This proprioceptive sensor is specifically deigned for use in the maritime environment due to the fact that only in water will acoustic/ FM sonar sensors provide the best wave propagation and resolution.  To note, one of the greatest advantages of this particular sonar imagining sensor is that is uses full spectrum signal processing that sends out a broad band transmitting pulse. One benefit of a full spectrum system is the relative power savings over a conventional continues wave sonar system. In order to obtain the same resolution, conventional sonar would required 100 times more power compared to the full spectrum sonar system (EdgeTech, 2015).

Possible Modifications

Upon analysis of the EdgeTech 2200-m on the Bluefin-21, other than attempting to decrease weight and power consumption, which are key to any unmanned system, I propose that the ability to network multiple sensors via underwater acoustic networks should be integrated. Due to the temporal constraints of any search and rescue mission, being able to cover larger amounts of area in less time is essential. The Bluefin-21 uses an INS to accurately track its positions, but allowing the position data to georeference the EdgTech’s imagery would be the first step in the multi-sensor integration (Bluefin-21, 2015). After georeferenceing, multiple sensors would need to communicate the data in order to run algorithms that would optimize participating AUV tracks so the multi-sensor system could map the largest possible area the least amount of time.

Aerial Integration

     In order to network multiple sensors via underwater acoustic networks, consideration must be made to the limitations of acoustic communication networks.  Underwater acoustic communications are generally recognized as one of the most difficult communication media in use today (Stojanovic, 2009). Due to this limitation, an alternative could be the introduction of an aerial command and control node, specifically an unmanned aerial system capable of extended transit and loiter times as well as beyond line of site communication of high bandwidth datasets. The multiple Bluefin-21’s could surface at regularly scheduled intervals and upload key data to the command and control UAS. The UAS would not only send the AUVs datasets to the mission command center at real near time, but it could also provide mission parameter changes to all other AUVs participating in a particular mission set. 

Unmanned vs Manned

            In terms of maritime sensors, there are a few key reasons why the use of AUVs over manned systems is beneficial. One major reason has to do with sensor depth. In terms of maritime sensor operation, it is known that attenuation of sonar pulses and noise are a limiting factor in obtaining high-resolution products (Stojanovic, 2009). If sensors were limited to shallow depths due being mounted on manned systems, the resolution during deep-water search and rescue would be limited. If the system is mounted on an AUV like the Bluefin-21, which is capable of diving to 4500 meters, it would be able to retrieve higher resolution products, and possible dive deep enough to obtain true camera imagery of the bottom of the ocean (Bluefin, 2014).

Conclusion

            The integration of unmanned systems into maritime search and rescue has taken previously existing sensor technology to the next level. The ability to take these sensors deeper and coordinate and optimize multi-sensor operations will save lives in the near future. By further integrating the unmanned aerial layer into the maritime layer, it will speed up data transfer and facilitate ad hoc mission changes.

   

References

Chand , N. (2014). Unmanned/Autonomous Underwater Vehicles. SP’s Naval Forces, Jun 2014 Issue. Retrieved from http://www.spsnavalforces.com/story.asp?mid=37&id=6

EdgeTech Corp. (2015). 2200-M Modular Sonar System. Retrieved from 

            http://www.str-subsea.com/file_download/22/EdgeTech+2200+Modular+Sonar+System.pdf

BlueFin Robotix Corp. (2015). Bluefin-21 Summary. Retrieved from http://www.bluefinrobotics.com/products/bluefin-21/

Stojanovic, M., & Preisig, J. (2009). Underwater Acoustic Communication Channels Propagation Models and Statistical Characterization. IEEE Communications Magazine Retrieved from http://web.mit.edu/millitsa/www/resources/pdfs/chmj-print.pdf