ECS Sources Sought.pdf

Sources Sought

The Army Contracting Command – Letterkenny Contracting Office (CCAM-ALK) is issuing this Sources Sought/Request for Information as a means of conducting market research to identify parties having an interest in and the resources to support this requirement for four (4) each Environmental Control Systems (ECS) to be used on mobile shelters. The result of this market research will contribute to determining the method of procurement. The applicable North American Industry Classification System (NAICS) code assigned to this procurement is 333415.

There is no solicitation at this time. This request for capability information does not constitute a request for proposals; submission of any information in response to this market survey is purely voluntary; the government assumes no financial responsibility for any costs incurred. Contractor should not provide any pricing information. The sole purpose of this request is to locate qualified, experienced, and interested potential sources.

If your organization has the potential capacity to provide these products, please provide the following information:

1) Business name, mailing address, email address, website address, Point of Contact (POC), telephone number

2) Business size, any socioeconomic status (i.e. HUB Zone,8(a) Veteran- Owned, Women-Owned, etc.), company Cage Code and DUNS number, type of ownership for the organization

3) Tailored capability statements addressing the particulars of this effort, with appropriate documentation supporting claims of organizational and staff capability. If significant subcontracting or teaming is anticipated in order to deliver technical capability, organizations should address the administrative and management structure of such arrangements

4) The NAICS code(s) and PSCs/FSCs your company usually performs under Government contracts

5) Past performance with government agencies.

The government will evaluate market information to ascertain potential market capacity to provide products or services consistent in scope and scale with those described in this notice and otherwise anticipated.

Based on the responses to this sources sought/market research, this requirement may be set-aside for small businesses or procured through full and open competition, and multiple awards may be made. Telephone inquiries will not be accepted or acknowledged, and no feedback or evaluations will be provided to companies regarding their submissions.

Contractors are required to be registered in the System for Award Management (SAM) and Wide Area Work Flow (WAWF) in order to be awarded government contracts.

Submission Instructions: Interested parties who consider themselves qualified to provide the listed are invited to submit a response to this Sources Sought by February 5, 2021 at 2:00PM (Eastern Standard Time). The response/statement of capabilities must be complete and sufficiently detailed to allow the Government to determine the contractor’s qualifications. All responses under this Sources Sought must be emailed to mary.e.shifflett2.civ@mail.mil.

If you have any questions concerning this opportunity please contact: Mary Shifflett, Contract specialist at mary.e.shifflett2.civ@mail.mil or 717-267-5375.

APPENDIX 1: Requirement(s)

PURCHASE DESCRIPTION

FOR

ENVIRONMENTAL CONTROL SYSTEM

1.0 General

1.1 Scope: This specification shall apply to an estimated quantity of four (4) Environmental Control Systems (ECS) used on mobile shelters containing electronics equipment deployed in a tactical military environment in support of the TPY-2 Electronic Equipment Unit (EEU) program.

1.2 Period of Performance (PoP): The Period of Performance shall be one Base Year of 12 months and one 12-month option year. Period of Performance reads as follows:

1.2.1 Base Year: 03 May 2021 to 02 May 2022

1.2.2 Option Year One: 03 May 2022 to 02 May 2023

2.0 S Specifications

2.1 The ECS shall provide heating, cooling, and humidity control to create an environment suitable for commercial-grade and military-grade electronics.

2.2 The ECS is the primary source of cooling, heating, dehumidification, humidification, filtration, and fresh outside air supply for equipment and personnel operating in an insulated, EMI/RFI shielded 41 foot shelter. It may be used either in the shelter known as the Electronics Equipment Unit (EEU) or the Concurrent Training and Test operations Support Unit (CSU). The purpose of the ECS is to maintain the EEU/CSU main compartment temperature and humidity within acceptable limits for the enclosed electronics and personnel. The ECS may use redundant or partially-redundant systems in order to meet performance requirements.

2.3 Available Equipment Spaces:

2.3.1 Condenser Compartment: The condenser will be a partially enclosed assembly on a space frame structure. The compartment will have a roof panel which can be removed to gain access for routine maintenance.

2.3.2 Evaporator Compartment: The evaporator compartment will be an insulated enclosure assembly on a space frame structure. Accessibility to interior components of the evaporator section for replacement or service shall be made through doors/panels that, when closed, do not compromise the NBS integrity of the EEU/CSU main compartment.

DRAFT

2.4 Physical design and construction

2.4.1 Weight: Evaporator Section shall not exceed 1,865 lbs. (excluding refrigerant).

Components in Condenser Section, including frame shall not exceed 3,500 lbs. (excluding refrigerant).

2.4.2 Refrigerant shall be in accordance with A-A-58060A.

2.5 Performance Requirements

2.5.1 Operating Modes: The ECS shall have two states: “ON” and “OFF.” The “ON” state indicates that the ECS is powered and is controlling temperature and humidity. This is also referred to as the “operating” state, and includes the Start Up, Transient, and Steady-State sub states. The “OFF” state indicates that the ECS is not powered. This is also referred to as the “non-operating” condition. Storage requirements assume the ECS is in the “OFF” state.

2.5.1.1 Sub-States of the ON state

- Start Up sub-state: The ECS is on, but the temperature and humidity conditions in the ECS/CSU main compartment are outside the bounds. The EEU payload electronics cannot safety be energized when the ECS is in Start Up sub-state.

- Transient sub-state: The ECS is ON, and the temperature and humidity in the EEU/CSU main compartment are within the bounds, but not within the steady-state bounds. The EEU/CSU electronics can safely be energized while the ECS is in the TRANSIENT sub-state. The ECS may go from STEADY-STATE to TRANSIENT under the following circumstances:

a) a temperature change is commanded by the user.

b) an auto-restart occurs.

c) the heat load inside the EEU/CSU changes by more than 10%.

The ECS shall recover and return to STEADY-STATE within120 minutes.

- Steady State sub-state: The ECS is ON and is maintaining temperature and humidity in the EEU/CSU main compartment within the bounds.

2.6 Operating Requirements: The ECS shall meet performance requirements continuously, without interruptions for maintenance, for not less than (nlt) 96 hours over a period of 45 days, under the worst-case combination of environmental conditions allowed. The ECS shall support 17 hours-per day operations, meeting all performance requirements, for nlt 75 days, under the worst-case combination of environmental conditions allowed. Each time the ECS is cycled ON, the redundant component set energized shall be alternated from that of the previous ON cycle.

Additionally, the ECS shall automatically cycle to the redundant system if a fault is detected which would prevent the running system from maintaining EEU/CSU internal environmental control. A manual override which forces the use of a single system (disabling auto-switchover) shall be provided. The ECS shall meet performance requirements for 24 hours, during which continuous humidification is required, without refilling the humidifier reservoir.

2.7 Internal Environmental Control: The ECS shall maintain the internal environment of the EEU main compartment within the requirements with a heat load of between 0 and 153,683 BTU/hr. (45 kW) deliverable capacity, including 30 kW from payload electronics, environmentals and a maximum of three operators, in any combination of the environments. The ECS shall be sixed to account for heat generated within the ECS, including but not limited to the fans, heaters, wiring and motors.

2.7.1 Steady-State Requirements: When in a steady-state condition, the ECS shall maintain the air temperature in the EEU main compartment at the primary control location at a selected steady-state temperature between 70o F (21oC) and 75of (24oC) Dry Bulb. The temperature shall be stable and accurate to the selected temperature with +/- 2oF (+/- 1oC) at the primary control location. The temperature variation across the shelter shall not exceed +/- 10oF. The ECS shall control relative humidity inside the EEU main compartment between 30% and 60%. Within that range, the humidity shall be stable within +/-5%. The desired steady-state temperature and steady-state humidity shall be adjustable through a lockable human machine interface.

2.7.2 Transient Requirements: While the ECS electronics are operating, if a temperature change of more than +/- 2oF (+/-1oC) is commanded, the maximum rate of temperature change inside the EEU main compartment shall not exceed 8oF/hr. (4oC)/hr.). The ECS shall prevent the EEU main compartment air temperature from exceeding 90oF (32.2oC) or dropping below 68oF (20oC) at any time during operation. The ECS shall prevent the EEU main compartment humidity from condensing in any internal equipment and on any interior surface of an exterior wall who’s temperature is above 40oF, and from exceeding 80% of dropping below 20% at any time.

2.7.2.1 Startup Requirements: The rate of temperature change shall not exceed 36°F/hr.

(20°C/hr.) at any time.

2.7.2.2 Start Up Timeline, Normal Operation. When the ECS is energized, it is in the START UP sub-state. The ECS shall meet the steady-state temperature and humidity requirements within 60 minutes of being turned ON, given the following conditions:

a) 0 BTU/hr. electronics heat load.

b) Ambient temperature between +41°F (+5°C) and +100.4°F (+38°C).

c) Daylight and dry, clear weather.

d) No Nuclear, Biological, and Chemical (NBC) threat (Mission Oriented Protective Posture -0 (MOPP-0)).

2.7.2.3 Start Up Timeline, Adverse Conditions: The ECS shall meet the steady state temperature and humidity requirements of Paragraph 3.3.3.1 herein within 8 hours of ECS Power application when the external ambient temperature is between -26°F(-32°C) and +41°F (+5°C) or between +100.4°F (+38°C) and +121°F(+49°C).

2.7.2.4 Low Ambient -26oF (-32o C) Operation: EEU/CSU main compartment heating and cooling will be required at low ambient temperatures. The ECS logic shall determine when the compressors are safe to energize after the ECS has been turned “ON”. Low temperature operations shall maintain the compressors within safe starting and operating limits as determined by the compressor manufacturer.

2.7.3 Refrigeration System Operation

2.7.3.1 Low-Temperature System Protection: The ECS components must be protected from freezing during operation. The ECS shall provide protection to the compressors against liquid slugging, oil dilution, and other low temperature-related faults.

2.7.3.2 Structural Isolation: Components of the refrigeration system shall not carry structural loads.

2.7.3.3 Refrigerant Moisture Content: The moisture content of the system shall not exceed 60 parts per million by weight in the liquid state.

2.7.3.4 Condensate Drainage: Provisions shall be made for complete draining of condensate from the coils to the condensate drain pan under all conditions. In the event of a chemical threat, chemical agents shall not enter into the circulating air stream through the condensate drains. A “duckbill” check valve may be used to accomplish this. The ECS design shall prevent insects from entering the condensate drains. The drainage system shall prevent the formation of standing water. Condensate from the evaporator coils shall be prevented from re-entering the supply air stream.

2.7.3.5 Refrigerant Lines: When parts of the system are located in both the front and rear compartments of the shelter, connecting refrigerant lines shall be run such that they do not protrude beyond the outer boundaries of the shelter and do not interfere with access to the main compartment. ECS design and/or insulation shall prevent dripping due to condensation on cold lines. Design analysis, fabrication, and inspection of the refrigeration piping system shall be in accordance with American Society of Mechanical Engineers (ASME) B31.5, Refrigeration Piping.

2.7.4 Minimum Controls/Safeties.

2.7.4.1 Safe Operating Pressure: The system shall shut down the operating system in the event maximum or minimum safe operating pressures are exceeded. The safety device(s) shall have an automatic reset feature to allow ECS operation either immediately, using a redundant system, or after the pressure returns to a safe level.

2.7.4.2 Circuit Protection Devices: The ECS shall have a main circuit protection device accessible from the ECS control panel. The main circuit protection device shall provide overload and short circuit protection for the entire system. Additional circuit protection devices shall be incorporated as recommended by the National Electrical Code (NEC).The circuit breakers within the ECS shall provide selective protection such that only the circuit protection device closest to the fault is tripped. Redundant systems shall have circuit protection devices which shut down all components of one system without affecting components of the other (redundant) system.

2.7.5 System Status Data Logging: The system shall automatically record system health and status data for remote troubleshooting and failure trend prediction. Data shall be retained automatically for a minimum of 14 days. Where applicable, the redundant equipment shall have independent readings. The data should be accessible for download and analysis within one hour of being recorded. The following items are examples of the types of data which should be recorded:

a) Internal air temperature(s).

b) Internal humidity measurement(s).

c) On / Off status of compressor(s), fans, motors, humidifiers and heaters.

d) Energized / de-energized status of valves.

e) Refrigerant system pressures (suction, discharge, liquid line, evaporator discharge, etc.).

f) Refrigerant system temperatures (suction, discharge, liquid line, evaporator discharge, etc.).

g) Status of control power.

h) Phase / Voltage / Current Fault status.

i) Ambient temperature.

j) Status of replaceable items (filters).

k) System runtime.

Data logging equipment is Built-In Test Equipment (BITE) and is therefore not mission-critical equipment.

2.7.6 Control Panel(s): The ECS shall be supplied with control panels which contain a full complement of controls for all the sub-systems in the ECS. Components of the EEU/CSU control/display panels, patch panels, and other panels shall utilize functional grouping. The ECS shall prohibit activation of controls in improper sequence for functions that may result in a hazard. A test button or switch shall be provided to prove the functionality of all indicators.

Visual indicators shall be provided for (at a minimum) all Hardware Effective Function Faults, ECS ON/OFF status, ECS START UP/TRANSIENT/STEADY-STATE status, MOV status, Voltage Monitor status, the status of redundant systems, and the current temperature and relative humidity levels in the EEU/CSU main compartment. Temperature and humidity levels should be displayed numerically inside the EEU/CSU.

If a remote/secondary panel is provided, the following controls shall exist in the remote panel.

Other controls may exist if space is available.

a) System Power Switch and system power indicator light.

b) ECS START UP/TRANSIENT/STEADY-STATE status.

c) Redundant System Selector Switch and active system indicator light.

d) Indicator Light Test Switch.

e) Fault Status.

f) EEU/CSU main compartment air temperature and relative humidity.

2.7.7 Control Circuitry: All control circuitry shall be contained in one or more waterproof, EMI-shielded enclosures. All control and power wiring between the evaporator and condenser compartments shall be EMI shielded.

2.7.8 Fault Monitoring: The ECS shall have a Voltage Monitor and Phase Rotation Failure Relay which detects when a power phase is lost or mis-rotated, or when the voltage deviates more than ±10% and automatically shuts down the ECS. The Voltage Monitor and Phase Failure Relay shall automatically restart the ECS after corrective action has been made.

A Fresh Air Flow Sensor shall be provided on the fresh air make up line to verify operation of the fresh air make up damper and/or the Gas Particulate Filter Unit (GPFU). This sensor shall provide a switch closure to activate an audible alarm in the main compartment if fresh air is not being supplied at a rate of 60 SCFM or greater.

2.8 Physical Requirements

2.8.1 Accessibility: When the ECS is installed in the EEU/CSU, access to every major unit, subassembly, and diagnostic aid shall be through removable access panels or doors. The ECS shall be constructed to permit access (in accordance with MIL-STD-1472) to interior parts, terminals and wiring for inspection, repair, removal or replacement of line replaceable units (LRUs). It should not be necessary to displace or remove wires, cables, subassemblies or assemblies to access LRUs. Line Replaceable Units (LRUs) include all those items which are field-replaceable. Depot repairable/replaceable items do not need to be removable without displacing other components, but shall be accessible for inspection and any required maintenance. All panels or covers on the equipment which must be removed or opened for servicing or making adjustments shall be retained with captive hardware. Components which are subject to replacement or servicing shall not be permanently secured by rivets, welding, inaccessible fasteners or other means which would preclude their removal. All filters shall be located such that replacement and routine service can be accomplished. Access to all lubrication fittings on machinery bearings is required. Cables shall be permanently installed and require no removal for transportation.

2.8.2 Nuclear/Biological/Chemical (NBC) Integrity: The ECS shall withstand, without damage, the effects of NBC contaminant exposure and subsequent decontamination wash-downs with Supertropical Bleach (STB), High-Test Hyperchlorite (HTH), and Hot Soapy Water (HSW) not less than five times in a 30 day period. The presence of features which would prevent decontamination of the ECS should be avoided.

2.9 Power Requirements

2.9.1 Electrical Interfaces: The ECS shall operate from an Input Voltage of 480V +/- 10%. The ECS will be fed from a wye configured transformer secondary. This will be a four wire feed (no neutral) and the wye secondary neutral will be connected to ground using a high resistance ground configuration. See Figure 2 herein. The input frequency will be 60 Hz +/-5%. Input short circuit current will not exceed 10,000 A RMS with a bolted short at the ECS input terminals. The

ECS shall not require more than 110 Amps RMS max long term, 500A max for less than 0.2 Seconds. Time delays may be used to manage inrush current. Input power shall be no greater than 73.0 kW/91.25 kVA at worst case operating conditions. The power factor shall be no less than .80 lagging. Three properly rated MOVs shall be connected in a star configuration and the common point tied to chassis ground using a fourth MOV as shown in Figure 2 herein. The GPFU shall be supplied with 60Hz, single phase, 120VAC at 20A power from the ECS via a step down transformer. All electrical components and wiring shall be properly de-rated to meet environmental requirements specified herein. The electrical design and implementation shall meet NFPA-70 National Electrical Code 2008.

2.9.2 Auto-Restart: The ECS shall recover and autonomously return to normal startup operation after a prime power interruption of up to 5 minutes in not greater than 1 minute thereafter. The ECS shall recover and return to normal startup operation after a prime power interruption of up to 2 seconds in not greater than 15 seconds thereafter. In both cases, the ECS is only required to return to TRANSIENT mode operation within the specified time.

2.10 Testability Requirements

2.10.1 Fault Detection: 99% of all ECS hardware essential function failures (HEFFs) and 95% of all ECS non-HEFF faults shall be detected. All critical ECS fault indications shall latch on during the existence of the fault condition.

2.10.2 Fault Reporting Latency: During ECS operation, HEFFs shall be detected and reported within 2 seconds. Non-HEFF faults shall be detected and reported within 2 minutes. The following faults shall be reported to the Signal Data Processing Equipment (SDPE) as normally-open contact closures (open on fault condition, close on non-fault condition) indicators:

a) ECS status (no fault/fault) (duplicated for redundant sides, if applicable).

b) EEU shelter under temperature

c) EEU shelter over temperature

d) ECS humidifier water level low.

e) Fresh Air Damper Fault.

2.10.3 Fault Isolation: 99% of all reported failures of the ECS shall be isolated to one LRU using a combination of BIT/Built-in Test Equipment (BITE), visual operations/inspections, and/or automated maintainer controlled fault isolation subroutines used in conjunction with test equipment.

2.10.4 False Failure Indication: The ECS false failure indication rate shall be not greater than 1 percent of the failures reported over the lifetime of the system.

2.10.5 BIT/BITE Failure: ECS Built-In Test Equipment (including the data-logging equipment) is not considered mission-critical equipment. BITE shall not degrade the performance of mission-critical operations.

2.11 Environmental Requirements

2.11.1 Operating Temperature Range: The ECS shall meet performance requirements in ambient temperatures of –26oF to +121oF (-32oC to +49C) with solar radiation of 0 to 1120 W/m2 (at +42oC) or 0 to 701 W/m2 (at +49oC) with no degradation in performance.

2.11.2 Storage Temperature Range, Non-operating: The ECS shall not sustain damage when stored in ambient temperatures of –50.8oF to +160F (-46oC to +71oC).

2.11.3 Operating Altitude: The ECS shall meet performance requirements at altitudes from sea level to 8,000 feet (2.45 km) above sea level.

2.11.4 Operating Humidity: The ECS shall meet performance requirements in environments with relative humidity tending towards saturation at all temperatures not greater than +87.8oF

(+31oC), or at relative humidity decreasing to 75% at +95oF (+35C), 20% at +109oF (+43oC), and 3% at +120oF (+49oC).

2.12 Design and Construction.

2.12.1 Materials, Parts and Processes: The ECS Parts, Materials, and processes (PMP) used shall be as specified in the Radar EMD Parts, Materials and Process Plan, MSRI Program, Parts Obsolescence Management System Analysis, and the applicable specifications specified herein.

Materials or processes which are not covered by applicable specifications or are not specifically described herein, shall be selected from Army document 13553906 unless otherwise approved.

Materials or components subject to rapid deterioration due to the environmental requirements imposed herein shall not be used. The use of Military Off The Shelf (MOTS) or Commercial Off The Shelf (COTS) shall not affect the ability of the ECS to meet its performance specifications.

2.12.2 Materials

2.12.2.1 Dissimilar Metals: Unless suitably protected against corrosion, dissimilar metals couples as defined in MIL-STD-889 shall not be used in intimate contact with each other. When parts of dissimilar metals are in contact with each other, the contact faces shall meet the criteria for metallic couples defined in MIL-STD-889 for the appropriate environment.

2.12.2.2 Corrosion Resistance: Corrosion prevention and control shall be in accordance with Army document 13553905.

2.12.2.3 Electrical Connections: Electrical Connections shall be made with liquid-tight conduit and waterproof enclosures.

2.12.2.4 Mechanical Fasteners: Anti-seize compound shall be used on mechanical fasteners, excepting 1/4 turn fasteners, exposed to corrosive environments that are not otherwise sealed.

2.12.2.5 Non-Metals: All non-metal parts used, such as plastic, fabric, and insulation, shall be moisture, fungus and flame retardant. Products derived from wood or wood fibers shall not be used. All non-metal parts shall be resistant to chemical agents and their decontaminates.

2.12.2.6 Flammable Materials: Materials shall be noncombustible or fire retardant in any combination of atmospheric, pressure, and temperature (ambient or induced) conditions within the limits defined herein. All materials used shall have a minimum flame spread rating of less than 25 when tested in accordance with ASTM-E162-1998E1.

2.12.2.7 Hazardous Materials: The ECS shall not use or contain any of the Class I ozone depleting chemicals (ODC) as listed in "Section 602" of the Clean Air Act. The ECS shall not contain or use any of the Environmental Protection Agency (EPA) listed set of highly toxic substances without specific approval of the procuring activity. The ECS shall not contain or use any of the DoD "Top 10 Toxic Release Inventory (TRI) List of Hazardous Chemicals" without specific approval of the procuring activity.

2.12.3 Parts: Standard parts (MS, AN or JAN) shall be used and shall be identified on drawings by their military part numbers. In the event there is no suitable corresponding standard military part, commercial parts may be used provided they conform to the overall requirements of this specification. When commercial parts are utilized, the equipment manufacturer shall cross reference their assigned part numbers with those of their suppliers on all drawings and spare parts lists such that the original source and part numbers of those components are readily identifiable.

2.13 The contractor shall supply all equipment, parts, and materials outlined in the drawing.

3.0 E quipment Nameplate: If and where applicable, a corrosion resistant metal nameplate shall be securely attached to the equipment. The ECS system nameplate shall include the contract number, official nomenclature of the component, the vendor CAGE code and part number and the serial number. Nameplates shall be securely and permanently mounted and not be obstructed from view by units or parts. Nomenclature characters on the nameplate shall be no less than

0.187 inch, and other characters shall not be less than 0.093 inch in height.

4.0 Testing:

4.1 The following acceptance tests shall be performed on each ECS:

a) Visual Inspection;

b) Dimensional check;

c) Evaporator fan airflow and static pressure;

5.0 First Article: The ECS shall be subjected to the first article verification as outline in the drawing. Verification shall be performed before installation into the EEU/CSU unless otherwise specified.

6.0 D rawings and Manuals: All specifications and requirements in the drawing shall be followed.

7.0 Warranty: If the warranty period is less than one year, it must be approved to by the LEAD Contracting Officer prior to contract award. Otherwise, a minimum of a one year warranty shall be furnished with the provided equipment. The warranty shall cover all components. The warranty period begins when the LEAD Contracting Officer provides official confirmation that the equipment has satisfied all operational provisions of the contract.

8.0 S tandard Products: The equipment shall be new and regularly advertised product in order to provide a constant source of replacement parts and technical assistance.

9.0 P reservation, Packaging and Delivery: The requirements for packaging shall be sufficient to afford adequate protection against corrosion, deterioration, and physical damage during shipment from the manufacturer to the point of delivery, and may conform to the manufacturer's best commercial practice when such meets these requirements. The ECS, in its transport configuration, shall be transportable worldwide over air, ground, rail, and water as one or more individual units (requiring no major disassembly), using existing transport aircraft and/or equipment. Major disassembly is defined as disassembly requiring more than 30 minutes.

10.0 Inspection and Acceptance: The provided equipment shall be examined for design, construction, materials, components, and workmanship to determine compliance with the contract and this specification. Any deviation from these requirements shall be cause for rejection.

11.0 O fferor’s Proposal and Compliance: The offeror’s proposal shall clearly demonstrate that the proposed equipment meets the detailed performance and equipment specifications described in this document and drawing. All information required to verify compliance with this specification shall be provided, (i.e. manufacturers specifications, drawings, brochures, etc.).

12.0 Safety: Safety engineering principles and design guidance shall be in accordance with the Occupational Safety and Health Act (OSHA) as identified in Code of Federal Regulations (CFR) Title 29, Part 1910. MIL-HDBK-454, Guideline 1 should be followed.